But the reason for the shorter partitions isn't generally cost.
1. Security: you can see if someone is still in the toilet when it is closing time, etc.
2. Cleaning: it is easier to clean with a gap, more clearance for the mop.
What I really wish we would get is stall door locks that indicate if locked or not. A properly hung stall door should naturally move to the open position but most are not properly hung. So you have a row of stalls all with the door closed and no idea if they are occupied or not. Which means you are either pushing on the doors, looking under or through the gap. It's Barbaric.
ADA Standards: 604.8.1.4 Toe Clearance
Those reasons are valid, but I'm not sure they beat "my vendor has a kit for this."
Like, even if you wanted a partition that went to the floor, a lot of vendors don't even have them. That's why I say precedent is a big reason why.
Wait......that's not standard in the US????? I've never seen a bathroom with a door lock that doesn't show its state on the outside, even if it's a simple mechanical latch.
The "moving part" doesn't go through the door.
Fancier bathrooms have deadbolts or equivalent that show the occupancy on the outside; amusingly enough so do the portapotties.
This is so simple (turning the lock reveals a patch of green or red) and useful that I can't really believe this is uncommon anywhere.
Also USians are used to it, so we don't complain :)