Note that, as I understand it, the security checks and queues for Chinese high-speed trains are comparable to those required at airports elsewhere if not worse.
For what it's worth I've traveled on them about 15 times over the last few years, mostly to or from Shanghai and while it's comparable I'd say it's still way easier than an airport. At a glance though it definitely looks very crowded though because there is only one very large departure lounge (at least in Shanghai). In the smaller cities though you don't have the same crowds and the whole process is very quick and easy.
Security involves putting your bags on a conveyor that goes through an x-ray machine but no one actually has their bags opened so it moves quickly. Boarding is much quicker because a train has a lot more doors than an airplane.
However the queues to get to the metro/subway/underground system can indeed be horrifically long.
Not really. It’s basically a metal detector conveyer belt out front with very little flow control, fast to get through and not much thought going into finding anything. Compared to airport security, it’s a breeze (but it might have changed since 2016?).
