Because without planning there would be only houses and no daycare. Apartment complexes are the most profitable type of building (everybody needs an apartment to live), at least in my country, and daycares and schools are other infrastructure are not profitable and not worth investing if investor had a choice. They are a burden. So they make investor have no choice and carry a burden.

In SF, which has alot of old buildings (relative to US suburbs), most daycares run out of the first floor of a house. Same for many of the local, walkable neighborhood retail corridors, it's just not as obvious because the first floors were converted to retail and restaurants 80-100+ years ago and it looks like they were always there. Sometimes an extra floor of residential was added to make way for the ground-level commercial; cheap at the time as you only needed to meet basic safety codes.

Then zoning happened and the process stopped, particularly for retail and dining. Zoning means it's expensive to convert residential spaces to commercial, and vice-versa, if you're allowed at all. So to make it work you gotta build new and bigger. But that's expensive, and the way commercial financing works means new commercial construction only pencils out for chains. The numbers work even if the space would stay empty, because even a bunch of small shops couldn't afford the rent that needs to be advertised for the space to make the financing pencil out.

Basically, zoning causes problems that are then addressed with more regulations, which causes more problems.

And also, people need to adjust their expectations. Small commercial and services spaces will rarely be able to bring in enough revenue to pay rent in a brand new multistory steel building, no matter the floor area. These businesses can only thrive in old buildings, at least in advanced, high-labor cost economies. But you can't build new old buildings. All you can do is make it cheap and easy for the market to repurpose existing spaces to meet demand, and do this everywhere, not just in a corridor you're planning for (otherwise you're not actually allowing low-end spaces to emerge; a Starbucks will snap it up; there's needs to be enough of these spaces to allow the entire market to shift down). But zoning and approval processes create an economic environment antithetical to this.

If you want to keep your zoning and planning but are frustrated the free market doesn't do what you demand it to do, the state needs to build the darn spaces themselves and rent them out. But they don't like to do that because, shocker, it's really expensive to do things the way they demand. When the state (and community via taxes) has to internalize the costs of these demands directly rather than point fingers, it turns out they have trouble justifying the expense.

Where do those kids go to daycare now?