Are you suggesting that Hornby bring to market a product that is not compatible with a basic track component from another part of the Hornby brand stable of products.
Shame on you
However, based upon previous posts, there are issues other than the power connector with these mail coaches. Like for example, the inability to fit the operating ramp to some Hornby track pieces. Search "Mail" in the forum search box to find details.
Ah, it's a bit of a leading question ...
I have a R401 blue/grey mail coach from the mid-70s and that catches on the power clips (but not on points, interestingly). Also, I have a standard twin track oval and because the collection and ejection flaps are on opposite sides, there isn't enough room between track centres to fit either the collecting hook or bin, depending on direction of running. I can get the operating ramps to fit.
My kids really like it, though, so I thought that if I get a modern version, where the collection and ejection are done on the same side, then the issue of not being able to fit the trackside accessories goes away.
I've read the other threads, so will probably revert to glueing them onto the track if necessary.