PC: I look at the broken wain. Fixing it should be easy. It clearly just needs to have some parts nailed back in place, reset this brace, and a support put here.
GM: Um, are you a wizard or a wainwright?
PC: Wizard. But my Mental score is 15. I can figure things out.
So, what about these sheets that are covered, top to bottom, with references to the rule book? Where's the PC freedom? "I know how to fix wains." Okay, let me see your character sheet. Hmm. Your Crafting is zero, it says here. Sorry, not sorry. "But my Int is 15!" Okay, but your Background, Page, doesn't mention anything about wains. Being a wainwright takes Strength, and yours is 10 (wow, that's low!).
So I do play one of those detailed games.
Player: I try to fix the wagon wheel.
GM: make a crafting check.
Player: My PC doesn't have that skill trained, but it says I have +3. Rolls dice.
GM: Ok, after a bit of sweat and toil you figure it out.
Player: Now I want to carve a rune into it so it never breaks again and the wagon can hold a bigger load.
GM: That's a trained only task. You can do normal repairs and such untrained, but not special things.
Some things can be done untrained at one 'bonus' to your roll, being trained boosts your bonus, and unlocks tasks that requires training. The types of things that tend to fall into training are called out in the books because the system I use (Pathfinder 2E) has a lot of detail. Anything else is a judgment call of "Well, it's more like one of these trained things so it will require training" or "that's kind of a thing most people could figure out with some effort but trained people can do better". With the usual guidance being to have things fall into the 'figure it out' camp unless they're clearly 'just like' something in the trained only list.
For example, the Thievery skill:
Player: I steal the pie off the counter. GM: Sure, a trained thief would do this better, but any fool can try.
Player: I pick the safe. It says pick a lock is trained, this is a safe not a lock. GM: Lol... no. That's just playing with semantics. Pick a lock means picking locks - be they on doors, bikes, or even safes.