Why would EU building it themselves going to happen? Either it could be profitable for company to operate in EU or it is not. Assuming current US companies are efficient enough and if they couldn't be profitable, why could be a same thing built by EU is profitable there. In fact it is opposite as they couldn't track as much as American companies even outside EU.
Because US companies are hamstrung by US laws that prevent them from complying with EU law (i.e. US govt says you must give private data to us and EU says you can't give private data to non EU govt). Other companies not based out of the US can guarantee privacy that meets EU spec if they don't have local laws compelling data access. So it might not be EU companies that capatilize on it but there can be a market opportunity that US companies can't fill.
Because the US companies are bloat with their bureaucracy and structures.
A Google is not able to pull a startup thing.
See Stadia or the other short-lived projects, they all suffer from a lack of skin in the game - so to say.
