This is a good example of the situation in many sports. The UCI is a governing body, not an event organiser or promoter. Basically anyone can put on race, and they are responsible for making money out of it. So event promoters make their own deals with broadcasters.
Figuring out that I need to subscribe to GCN+, Peacock, and Flobikes in the US was no small feat (and it changes from year to year!).
I suspect the promoters try to keep away from the UCI as much as possible.
There have been a few attempts by the pro-teams to improve the situation via Velon[1][2] - apparently you can get live race data from them - but nothing that has really solved the problem.
[2] https://www.dcrainmaker.com/2018/01/velon-live-tracking-syst...