That's somewhat unfair.

In rail, it's more like is that there's nothing for 20 years, then the government announces one project. Everyone piles onto that one project and gold-plates everything because they already know there's not going to be any more projects after this one for 20 years.

Then the project overruns by billions.

The government pays, then vows not to make that mistake again, so they don't have any more projects for 20 years.

Rinse and repeat.

A much more healthy cycle is like the Italian build-out of high speed rail, where they have multiple projects going, working their way from one city to another, and the line is usable after each part is done.

(in the case of HS2, a lot of the blame can be laid at the feed of NIMBYs, and the government pandering to them. Oh you lovely Tory-voting home counties voters! Yes, it's essential we preserve this ancient forest and that protected species, I know, so important, we'll make the entire line underground for your part of HS2, of course we have the extra billions to pay for that. Fuck you, you dirty northerners. I've just had to stump up a fuckton more than expected to pay off my voters, so I'm cutting your part of the line. You'll be lucky if HS2 goes north of Birmingham)