Your whole argument is just trivially disprovable. Both trains and buses can be wheelchair accessible[1][2]. You don't need to lift the chair, you just roll it in, either up a slight incline in the case of buses or completely flat in the case of trains. No need for bystanders or station attendants to help.
[1] https://cdn.londonandpartners.com/visit/london-organisations...
[2] http://1.bp.blogspot.com/-1TZlXmiSe3I/UTcdowZY8hI/AAAAAAAAH3...