Have the patents for H.264 MPEG-4 AVC expired yet?

I find the video codecs situation very confusing.

Without even getting started on the insane fact that there are multiple names for the same technology (H.264 a.k.a. AVC a.k.a. MPEG-4 Part 10, related to H.265 a.k.a. HEVC a.k.a. ...).

I think that there being a patent on H.264 means that whoever manufactures a board that wants to support H.264 needs to pay royalties, which explains why some newer boards (like RPi) just let you use the CPU instead?

But then what does it mean that the patent of H.264 have expired in big parts of the world? Does anybody care?

Finally, there are open source alternatives to those. Why the hell don't we just all use them and forget about those patents?