I guess the architect thinks that will make it less popular/less likely to be used?
why do 98% of the rest areas put the HC stall all the way down the long row of stalls to the very end... and there is usually only 1 compared to 20 regular stalls
Let me try and answer this...
Designing HC stalls is not an easy task. They are supposed to have wider doors, enough width to accommodate the extra grab bars, and enough floor space to accommodate a wheelchair. Usually public restrooms are built back to back/men's to women's (aka if you walk into the men's room the stalls are to the left and if you then walked into the women's the stalls are on your right). This is the minimize the amount of plumbing required.
A HC stall should be a MIN 3'0" width of clear space and 4'8" MIN depth of clear space (preferred 5' even). The door width must be a MIN of 2'8" wide to accommodate a wheelchair. This is for a front transfer. To accommodate a side transfer you have a MIN width changing to 5' of clear space. Most designers I have worked with with use a stall made to accommodate the side transfer since it will also be fine for a front transfer.
This means this stall will take up the space of nearly 2 normal stalls. The plumbing though still has to match up. So the toilet will usually be situated to the left side of the stall (when looking at it straight on) since the partition will be in the spot of the other plumbing hook up.
If you add anything else into the stall like a sink or changing table, then you have to deal with now adding additional clear floor space usually meaning you have to increase the length, which then eats into the clearance outside the stall and for the door. Thus you end up having to do the stalls that eat up the whole back wall with the door to the side. In this case they HAVE to be all the way to the back because the literally take up a HUGE chunk of space in the restrooms. Honestly, most of the time the enlarged stalls just FIT better that way. Plus, the extra grab bar then has a solid wall and not just a partition to be anchored to. I once visited for research a restroom that had grab bars on the partitions... not the sturdiest things in the world.
Trust me, it is NOT easy to do a public bathroom layout with all the different requirements.
The number of total stalls is regulated by the buildings occupancy... we HAVE to meet those standards. As a designer, it comes down to space. If you have room for 6 toilet hookups, 1 HC stall will take 2 of those. So you end up with 1 HC and 4 reg (5 total). If you upped that to 2 HC stalls then you would then be reduced to only 2 reg stalls (4 total). So, if I have 6 hook ups, but have to have 5 toilets, there is no way to have a second HC stall without a full plumbing refit.
Hope that all makes some sense!