My old Kubota has one. I think you'll find it pretty common on compacts since it is not likely that they will be running long stretches across a field or something, but rather used in a way that involves a lot of stop and go, fast and slow, back and forth kind of operation.
/ Advice Please - Which Tractors offer ft throttle??
My Mahindra 2615 4WD (Gear) has one. It's nice for loader work. I can set the throttle on the steering column to my desired low/mid RPM setting, then use the foot throttle when I need a little extra oomph! digging in to a dirt/brush pile.