They are doing that in East Bay [1] on BART owned land. They had been blocked so far by the most virulent NIMBY trash leading to some of the most scathing coverage [2]. Most have been unblocked and are under construction. The one still being blocked is Ashby BART because of (say it with me folks), a "HIsToriC flEa MARkeT" (that mostly sells stolen goods)[3].
[1]: https://www.bart.gov/about/business/tod
[2]: https://www.nytimes.com/2023/05/30/magazine/housing-berkeley...
[3]: https://www.berkeleyside.org/2024/09/17/berkeley-ashby-bart-...