Flying in Europe, it is about a 50/50 chance as to whether you get on the plane from a jet bridge or you take a bus to the plane parked on the tarmac. In contrast, most US airports have jet bridges, even when the plane is small unless it is a very small airport.
Why?
Maybe something to do with ADA (Americans with Disabilities Act) compliance? Europe tolerates a lot less accessibility by necessity since they have so many older buildings, so maybe that translates over into having more tolerance for stairs when boarding planes?
The last time I had to disembark a flight on the tarmac instead of via jet bridge, it was still a switch-back ramp instead of stairs, and was fully ADA compliant.
“Europe” has different laws in different countries. The UK is incredibly keen on accessibility, but Germany is ablist as hell, for instance.
I know the UK has the equality act, but I thought that only applied to employer/employee relationships. Is there actually an accessibility requirement/law for customers/patrons like there is in the US?