You make good points regarding the disadvantaged in society, but unfortunately the numbers of special needs passengers, many of whom occupy multiple seats, are leaving less and less room for ordinary fare payers.
Seating capacity has already been reduced by adding wheelchair provision and baby buggy space.
Not many rural routes have a problem with overfull buses.
It's often VERY spiky. Wiltshire experience is that there may be 5 buses a day but a single service - the first one after 09:30 - takes most of the traffic. A rail quote from my inbox this a.m. -
"Counts a few years ago showed that nearly 70% of all daily footfall from there was trying to cram onto the 08:07" and that's for a station with around 10 services each way per day. So there is the perception of overcrowding - 7 out of 10 will tell you services are stuffed to the gunwales, when in reality 9 out of 10 are carrying fresh air.
Looking back up thread and the bus from Butlins to Taunton, I suspect that it's the 08:55 and 09:55 off Minehead that are busy, and the 10:55 though to the 17:55 may have plenty of space on them.
Noting the follow up while I was writing - what is the general loading across the who service, broadgage - do you have numbers from right though the day?