Snowflake is nowhere near a monopoly, and plenty of customers have moved from other vendors (Teradata, Netezza, etc) to Snowflake - showing that vendor lock-in is not as strong as it might seem.
If that's the case, then why aren't Snowlake and Google targeting query optimiziation with higher priority to lower end-user costs? There's no incentive in the market for them to do so - once you switch to them, you'll eat up the cost of quirks and learn how to avoid them the hard way.