Aircraft are wheelchair/handicap unfriendly transports that cannot be modified for traditional access for what amounts to less than 1% of the customers who use air travel.
I don't know if you've ever witnessed what it requires, but they have a special narrow wheel chair that fits between the aisle to get the wheelchair bound passenger to their seat, then it takes two attendants to assist getting the passenger from the narrow chair into their seat.
What happens to those passengers blocked from the aisle by a wheelchair bound person if there is an in flight emergency?
The smaller the aircraft, like regional jets, the greater the problem. If it weren't for our dimwitted PC efforts to accommodate everyone on the planet regardless of its unfeasibility depending on environment and the fear of litigation, people who are wheelchair bound should not ever fly. It places the crew and passengers in greater danger should an emergency occur.
The best advice for those traveling and bound to wheelchairs, take a train or private ground transport. The best way is hire a driver and an accessible van.