The excess baggage charges if you carried a mobility scooter would be astronomical
They are carried free of charge. Battery must be disconnected or immobilized in a different way. most battery types are allowed. Contact your airline before travel and let them know what your requirements are. Some ie ryan air limit the number of disabled pax they will take.
As of to the holiday companies a lot of the buses are not suitable for disabled pax. and how will the electric wheelchair be loaded on the bus some weigh over 100kg one bus driver can not lift that on.
I believe the ruling is reasonable adaptations for disabled people.
Most airports and airlines are very good and will do everything they can to help. (worst were MAD did not seam to know what to do and LTN were the staff were putting their hands out for tips best TLV and BHX)
And before I get attacked my wife is in a wheelchair