So in the suburbs, yes and no. You can absolutely have grocery stores next to residential areas. So like if you have a main (st)road that has a grocery store, there may be housing behind the store. Here's an example in my area (The Price Chopper is a grocery store). Residential zoning has bumped up against commercial zoning along the (st)road. Which means that the grocery store is next door for some of those people. Even a few blocks away is still pretty decent.

But let's say someone wanted to build a grocery store next to this school for some reason. The developer is willing to buy up some houses (and people willing to sell them) and bulldoze them down to make a grocery store. The city will NOT allow that. That's like a 99.9999% chance of never happening. Because that area is specifically zoned for strictly for residential and not commercial endeavors.

And it goes further. Let's say instead of a grocery store, the developer wanted apartments or townhouses/duplexes. That keeps with the residential character and zoning, right? It does, but this area is probably zoned for SFH only. Not for multifamily units. It'll never be built. At least not without overcoming significant local opposition.

This is actually being fought over in a neighboring suburb.

That's not to say zoning is always terrible. If I build a house and then some industrial building/warehouse or commercial chicken coop wants to be my neighbor afterwards, with all the loudness and smells that brings, that's not gonna be great for me. And if I want to move because my quality of life has decreased, who's gonna buy my house? Nobody. At least not for the price I want.

So zoning has its benefits. It's just a tool at the end of the day. But it can make things difficult when people do want change. It's not as simple as tearing things down and putting up something new and completely different.