Bill, I agree with you; your water pressure should be greater. Two possibilities occur to me. One is that you have a "water saver" in the faucet of each of these particular outlets. There would be no reason to have one on the commode water line, and none on the tub outlet. In both of these cases, you want all the pressure, get it over with, and it goes off (commode) or you turn it off (tub). The other two, shower and kitchen sink, can consume huge amounts of water when (as often happens) they are turned on and
run for a continuous period. Airstream Company may well have put the little washer-with-small-hole ("water saver") in the line just ahead of the shower head or aerator on the kitchen sink. The same
effect would be apparent if you had grit or other crud in the water line and it stopped-up the aerator/sprinkler head.

The second possibility is a kink in the line inasmuch as both of these are on the curb side. But aren't the tub and commode on that side also?

If you find anything, let me know.

Donald