> I think I am also right in saying that you can buy a road bike that is better than the ones permitted in the Tour de France.

Recumbent bikes have been banned since 1934[0]! Remarkable machines. I'd love to ride one in a civilized location one day.

[0]: https://en.wikipedia.org/wiki/Recumbent_bicycle

A very small number of teams aren’t well funded, have sponsorship issues, or whatever else and actually run less than top end components. I don’t recall who but there were bikes at either TDF or vuelta maybe last year with group sets which you could’ve just gone to the store and bought better ones.