Finance already beats tech, apart from that small handful of ultra high paying roles in that handful of companies like Google.

Only if you are a Trader or an Investment Banker (note not the other 98% of people working at the firm i.e. Tech, Quant, Operations, Finance, HR) in which case you are already the handful of people such as the ultra high paid at Google as either your career is going to be very short once they find out you can't make money or you are very good (very few people) and you will make a fortune.

Yesterday? When has tech ever beat finance in pay?

For engineers it almost always does, unless you are the top .001% of talent.

In London at least this was not the case. Startup salaries today are often at the same level as bank internships. The US (particularly SF) is a very different market.

You are comparing a bank to a startup which is an absurd comparison. Compare Goldman to Google and guess what Google wins (even in London).

Banking salaries have been static for 10+ years. Bank internship salaries are designed to allure and impress but 5+ years in and the salary does not change.

On another note there are some startups who can pay very very well in London but they do not advertise these salaries.

SF has no finance companies.