They're working on it. Excavation is indeed a pain, there's a lot of extra traffic recently due to the construction, and people complain about the noise too. But it's happening.

I don't expect it to help much with the Shabbat issue, but politics are hard to predict so we'll see.

I would imagine that excavation in Tel Aviv would be a huge pain, and previously there were a lot of security concerns with bunching people up in a metro. Perhaps now things have quieted down but the land has gotten very expensive.

Ah there is a metro plan! https://en.wikipedia.org/wiki/Tel_Aviv_Metro