The old slam door trains had separate first class carriages with doors that closed and smart white antimacassars on the seats. The ticket collector would hover apologetically in the doorway and stamp tickets with great respect. First class travellers thought their journey worth the expense of a comfortable, secluded carriage. If they found themselves sharing, they would not be exposed to bad language or farting, because it would be wtih genteel individuals with expensive smells who read or snoozed quietly.

The new trains have first class areas too; but because of Equal Opportunities (I assume) are barely different from the rest of the train. Plenty of standard class travellers sit unwittingly in first class and even the ticket collector does not notice the difference without checking the signs on the windows first.

“Madam you are sitting in an area reserved for first class travellers. Kindly move over there (to other end of same carriage) or pay an extra four pounds fifty for your journey.”
“Oh, I’m so sorry I didn’t notice…um…over there looks exactly the same as it is here. What does the extra charge pay for?
“Well madam um, we have these white things called antimacassars on the seats so that you don’t get the dirt from other travellers on your head,”
“Oh.”
A pause.
“Is that it?”
“Oh no, Madam. As you can see you are separate from the second class area.”
“How? There is no door. Oh you mean that little gap in the middle of the carriage? On that basis second class areas are also separate from each other,”
Desperately; “Well…It’s smaller, cosier.”
“Or just has less room. In fact there is not one inch of extra foot room, there are exactly the same uncomfortable chairs, and not even a door to close for some privacy, peace and quiet!. In fact no difference at all!”
“Apart from the antimaca…”
“…Yes apart from those. So is there any purpose in moving or any value in paying an extra four pounds and fifty pence? “
“Um…enjoy your trip Madam.”
“I rest my case.”

The only real advantage to first class is that you won’t inadvertently find yourself in bottom class; reading quietly one minute and stuck in the middle of a toilet the next. If anyone wants to use it they press a button which slides the door panel back to reveal the person inside. The fortunate ones are caught washing their hands.