I remember the days of British Rail when trains were often unreliable, late, cancelled, dirty, falling apart... sound familiar...?
Whilst there's no denying that many private train operators are shite, the railways really weren't any better under British Rail, in my experience.
Of course, it doesn't necessarily follow that a nationalised railway wouldn't work this time around, but it's also not necessarily the silver bullet some think it'll be either.
Could say the same about some other industries too.