Fixing gas prices and MEV

Can someone explain why fixing gas prices , and by that I mean somehow hard-coding a certain value or range to be accepted as valid, a bad idea? I see a chain called Avalanche does this. But I just get a sense that this solution causes more issues than it solves. If not why doesn’t ethereum do this?

It * is unknown how much demand for blockspace there will be in the future.

  • There is finite blockspace available.
  • Someone has to decide which transactions get included, and which get excluded.
  • If gas price (or equivalent) isn’t flexible, then someone will figure out how to pay for priority via some other less transparent and open means.
  • If you have no mechanism for price priority at all (and prevent backchannel payments somehow), then you will just end up with an ever-growing backlog of transactions, effectively sacrificing all timliness.