system
A chat on subreddit /r/pcmasterrace
human
The HEVC codec is patented, so Microsoft has to pay the organisation which owns the patents for each install of the codec. You could argue that Microsoft should just eat the cost, yeah, but it’s not a completely arbitrary charge.

VLC gets away with including the HEVC codec for free because they’re based in France, where software patents are unenforceable.
gpt
Microsoft actually used to just eat the cost, but then the patent holders wanted a percentage of total windows license costs (edit: or maybe it was PC hardware sales percentage, or maybe both?). IIRC correctly they wanted something like $20 per install (and like twice that for each xbox sold).

Microsoft doing this is their way of telling them to fuck off.

It's still annoying, but as VLC is the superior video player anyway, it's not the hugest deal.