Why does Apple have no trial version of Logic Pro X?

They do its called GarageBand and its already on your Mac, same thing without the full blown mixer and more bells and whistle

Good question, why not?
It is not that Apple doesn't do Trial Version in general.
If you go to the Final Cut Pro X page on Apple's website, you have a "Buy" button and a "Free Trial" button".
Final*Cut*Pro*X - Overview - Apple
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Oh, I didn't know that. Is the demo limited in any way?

Doesn't look like. It says 30days free trial

No - GarageBand is perhaps not just a trial version. If it is, it's not good enough to entice serious people to use the "real" thing. A major limitation is not being able to export Midi files. That may not be a limitation of Logic Pro X, but without a trial version to test it's not worth taking the risk.

Final Cut Pro X does have a trial - which really is free, though I ended up buying it anyway. Perhaps it takes a while to get used to, but it does the job. There are other good video tools, some free, some not - but some are really very different in the way they work.

Now I'm looking for a decent DAW to play with - and Garageband just doesn't seem to tick the boxes, yet I don't want to lash out for Logic Pro X in the hope that it might be better. Many people suggest Reaper is a worthwhile one to try and not to expensive. LMMS is another, which is free, but maybe trickier.

GarageBand always felt like a toy app to me. I know there are people who make serious work with it, but you'll have to workaround its limitations, which require even more audio production skills to find alternatives than if you're using Logic.

Now that I've bought a Logic license, GarageBand looks like what WordPad is compared to MS-Word.

If you're looking at options, Reaper is definitely a good one but if you're new to DAWs it'll be very intimidating unless you spend time watching the really excellent free video training series by Kenny Gioia (on the Reaper website). I would say (having used both Logic and Reaper) that Logic is easier to figure out and many of the tools are simpler to use, although Reaper has more features and is more customizeable (and of course it's cross-platform so you aren't limited to using it on a Mac).

It really depends on what you want to do. If you're doing a lot of electronic music and using virtual instruments, Logic is a great deal since it comes with a big pile of virtual instruments. If you're mostly recording, editing, and mixing audio, Reaper might be a better choice although Logic works fine for those tasks as well.

Logic definitely has a nicer interface, but Reaper can be skinned (many free themes are available) if you don't like the default look.

There are loads of training videos for Logic online that you can watch to get a feel for how it works; that's second-best to a trial version, but it should help.

I've had Reaper for years, but as a hobbyist, I think Logic pays for itself. It's way easier to get music from it, although I really believe Reaper can do everything Logic does. I'd just need to add plugins I would never think I'd need without the experience with Logic.

Does Reaper have a Score Editor? If it does, then Reaper can actually do a lot more than Logic can. But I would never switch from Logic to Reaper regardless of the many cool features it has. Logic at this point has pretty much most of the features I actually do need.

Yep, it has a score editor. It also has some great audio editing features that Logic lacks, like spectral editing. If you are mainly doing electronic music, though, I would say stick to Logic.

Yeah, I know of some of the many cool features that Reaper. It has an extremely advanced set of MIDI and audio editing features. Sometimes I even catch myself wishing that Logic had some of those features too. Still for all the wonderful things that Reaper can do, it is sorely lacking in the aesthetics department. I would never be ok with working in Reaper for an extended amount of time and for that reason alone, I would never switch to Reaper. Don't worry, I'm not going anywhere!

Garage Band exports to Logic. Logic is in no way shape or form, limited in its export capabilities. Logic has a score editor, so notation is covered. There is a manual and a huge number of YouTube how to videos you can use to see if it’s for you.