If passengers have the money to spend on first class tickets, by all means go ahead and spend. However, most travelers cannot pay the first-class or business-class airfares and find themselves flying in coach seats.
I have found that when notified well ahead of travel, airlines will provide seats up front of the cabin for those who are wheelchair bound. Make sure to ask the airline ahead of time.
Airlines can be wonderful with having electric carts waiting and wheelchair assistance from curb to plane, but it must be planned ahead of time. Ask, ask, ask. That is the way to get through the airports and airport security.
Also, when being moved through the system in a foreign airport where there are waystations and holding areas for the handicapped, make sure to be assertive. Let the assistants know that your flight is leaving and make sure that you get to the gate on time.
Once, in Spain, the system forgot us in one of the waiting zones and we almost missed our connecting flight. So, pay attention. The systems work well but be alert to possible problems.