My house remodelling is almost done. And I'm repeatedly impressed by the expertise of the craftsman. All these details that have to be done correctly, both for engineering and æsthetics.
One reason we chose this house is it has beautiful 30s woodwork; oak floors, mahogany moldings and baseboards. We've installed new floors in a couple of rooms that didn't have them. And I learned a new thing; when you add a floor to an existing room, you have a problem as to how the floor joins the wall. Walls aren't straight and you can't cut wood perfectly, so you end up with a small gap between the floor and the wall.
Traditionally, the baseboards are installed after the floor and cover this gap. But when you have existing baseboards you have three choices. You can remove the baseboards, install the floor to the wall, and reinstall the baseboards. That's the right way but it's difficult and can damage the baseboard. So you can try to undercut the baseboards; cut a thin sliver from the bottom of the baseboards and slide your floor underneath. One floor company tried that and it was a mess, now the gap is in the wall, not the floor.
The final solution is a "shoe". You lay the floor as close as you can to the wall, then cover the gap with a little bit of trim. (The picture above is misleading; it shows the floor under the baseboard so there's no need for a shoe). The common fix is 3/4" quarter round for a shoe which looks completely ugly. For just a bit more work you can have a nicely shaped bit of trim. Stain it to match and it looks like an extra baseboard detail, not a patch.
This wall vs. floor problem is one of hundreds of problems that come up during remodelling. Good craftsman solve these kinds of problems every day. It's a lot like software engineering, only a heck of a lot harder because you can't just recompile to fix your bugs.