TL;DR: In the last year, the Wikimedia Foundation has fired several union organizers, including those that worked on the Community Tech team - a team dedicated to building features for the volunteer community that edits Wikipedia.
As the Wiki Workers Union tries to get the Wikimedia Foundation to recognize their union, it is worth remembering that this is not the first time that the Foundation has worked against the community.
Wikimedia Enterprise is a betrayal of the volunteer movement community of Wikipedia editors, as the Wikimedia Foundation is providing privileged access to big tech AI companies to the Wikipedia corpus - a body of work that the Foundation does not own.
Movement volunteer communities contributed to Wikipedia under copyleft licenses - licenses that work to ensure that the work remains free (as in speech). The big tech AI companies do not license derivative works under copyleft licenses and often do not even attribute where the works came from.
This means that volunteers are working for big tech for free, and the Wikimedia Foundation is selling privileged access to that free labor.
It is against that backdrop that the current unionization struggle unfolds.
I believe the purpose of OSM was to counter Google cranking up the prices for companies wanting to use their maps (and because the Ordnance Survey wouldn't provide free access to their maps). Companies (small ones, not Google-sized ones) that want to use map data for their business want to be able to make money so if they're not allowed to use OSM then they will keep paying the likes of Google.