[williamdclt]

Mostly repeating what others have said but...

Trains get delayed and cancelled very frequently. They leave you stranded in the middle of nowhere because there's a technical issue fairly regularly: it's not a daily occurrence, but it's frequent enough that people will just go "ahhh classic british rail".

Trains are often packed, with literally nowhere to sit for hours-long journeys.

And this poor quality of service is very expensive. I know adults in their late 20s - early 30s with a fulltime job that choose to take the coach even though it's twice as long, because it's much cheaper. An ex-colleague was living outside of london, and spending £16k a year on train for commuting (you'd expect a big bill, but £16k is insane).

I'm sure there's plenty of countries that do worse, and as an infrequent traveller you'd probably be fine, but it's just... not great