This is an easy one. Everyone can grab, throw, trip, disarm, etc. It just requires their full action, since they're not trained well enough to do that while stabbing someone.
And they can get extra damage . . . if they crit, or roll really well.
Basically, normal people can accomplish this stuff, but if you're trained, you can accomplish it more quickly. If you spend your time learning magic, or tracking, or lockpicking, you won't be spending as much time learning clever combo attacks.
I'm not sure I'd go even that far. I think that the only people who should be able to attempt to trip/disarm/whatever are people who've actually trained a lot to do those sorts of things. Occasionally someone who isn't as trained might do so almost by accident (roll a Crit), but it's not something that people should do nearly as well as someone highly trained in a particular skill. It's not as if just anyone can regularly paint like Titian, sculpt like Michelangelo, run like Usain Bolt, dance like Fred Astaire, or whatever other physical act they want to perform. You have to train for it.