There's a fish store here in town (SF), and the owner claims the following:

Filters - none, not needed
Water change - never do it, only top off
Plants - fairly heavy
Water movement - none

Air stones - none
Sponge filter - none
C02 - most tanks not

Substrate material - gravel
Ferts - some kind of substrate bars he sells that he puts under the gravel, says one pack lasts at least a year

Fish stock - he says you can have as many fish as you want

Lighting schedule - no idea, looks like moderate- low light
C02 - none on most tanks
Gallonage - don't know - probably 50g+, but he has some smaller nano tanks.

Water column - he says he only uses "bacteria" additives that provide beneficial bacteria liquid to regulate the tank and remove any harmful traces of nitrites, nitrate, ammonia.

He is an old school guy, and very nice, and his tanks look good, and his been in business for a while, but wondering how this is possible. His stock is always pretty legit. I bought some shrimp from him and tested the water in the bag and got the following:

Ammonia - .5ppm (like SF tap water)
Nitrates - 5ppm
GH - 6
PH - 7-7.2 ish

Is this too good to be true or does he have the magic? All tanks are pretty heavily planted, at least 70-80% plant mass. Also, this is a store, not like some random person just saying "I did this" - he's got like 50+ tanks running like this, and it's not some big box or ADA type operation.

Separate tanks or one large system feeding all tanks? I would not buy into being able to stock as many fish as you want if there is no filter nor circulation! He may be thinking of tiny little fish or something as nobody I know would attempt to stock many large fish without either.
Sometimes we get folks who have a single special niche in mind and make it work and when they speak it really only fits what they are doing. Also there are those who do not call a big central sump in the back a filter.
More details would be required to guess what and how it works for them.

This can be done. In fact if you look at very old aquarium books, from the 1940s and before, this was a fairly common setup. At that period of time, items like air pumps and filters were comparatively expensive, so you only put them on really "high end" systems.

The question really comes down to, is this a good way to keep tanks today? I don't think so. The newer equipment and the knowledge available lets you set up a tank and get a lot better results, and get then a lot faster.

Now I have not seen any of these tanks, but I think it's a safe guess that the plants being used are low light, easy to care for, undemanding plants. I don't think such an "old school" system could maintain many of the plants people want today.

I recommend that you use the newer methods and knowledge, unless you want to try an experimental tank using the old ways. Think of it this way, would you want to go back to using a telephone from the 1940's or keep your new smart phone?

It really doesn't sound alot different than a walstead tank with some differences.

Yes it is definitely possible. And assuming it's the store that I think it is (I also live in SF), it's been that way for a long time. I think a good deal of his secret is the heavy planting.

I'm going to get yelled at, but that's nothing new.

If this is such a great way to keep a tank, why is there ammonia readings? Shrimp don't produce that much in a trip home. If they were stuck in a bag for a few days while being shipped, then I could see it.

I continue to believe in balance. Balance of plant mass to stock level...balance in light and ferts...AND routine (if only modest) partial water changes. Plants are great at absorbing pollutants as nutrients, but they can only do so much...so I also use filters and air.
It's a confined, closed system and we should keep it fresh.
Ever heard anyone say we should start a tank with swamp water?
Keeping fresh water fresh is the best way to extend the lives of our healthy, happy aquatic friends.

I mean, telling people they can keep as many fish as they want probably isn't a great idea...

It's indeed very possible, my late father did just this, with some adaptions. Also, like others have stated, it is actually incredibly close to the Diana Walstad method, well, the method she made famous, but certainly didn't invent as such. Modern day equipment certainly helps depending on what you are wishing to achieve, size of tank, type of creatures in the tank and more. I would say he's an older gentleman who is doing something that works for him, with a little too much confidence in advising as a blanket statement, it'll be perfect for every situation and everyone.

Whilst there are many wrong or immoral things to do in this hobby, much of the products, techniques and so forth are all just personal experiences. Personal to your water supply, where your fish were imported from, how they were then treated by the LFS, the breeding lines, the light of the tank, the quality of light, the temperature in the tank, the quality of the plants, the differences in this and that and this and that. You get the idea.

Simply put, if everyone around the world followed the exact same "rules" as such, it would not be the case you'd see the same results. So I always recommend anyone joining this hobby, or anyone in this hobby for a while, to take all the advice they can, and do what works for them personally. So take aspects of common sense, plant knowledge, biology and so forth. Combine all of this and do what works for you.

Simply put, he's not completely wrong, but not right at all for many depending on what your equipment, circumstances and so forth are.