Yep I second this, Grid is £55 in the UK which is mega money for a game that may have an annoying amount of input lag,
It would suck to buy it then find out I can't refund it afterwards and have an expensive game which I'll never play.
That's a very good idea, I would love a demo before purchasing a game too!
You can request a refund within 14 days of your purchase if there is less than 2 hours of play time across all accounts (family and personal). Games may only be returned one time, so if you return a purchased game for a refund and subsequently re-purchase it, you will not be entitled to a refund. This refund is only available for purchased games, and not for add-on content or services.
see:
https://support.google.com/stadia/answer/9598538?hl=en
That is risky if it's anything like steam they keep track on how much you refund and notify you, "this is not a game try feature" they take note how much time you return games.
NOW as a pro user - the best solution would be give us 2 hours of free gameplay as soon as you use this you can no longer REFUND the game if you decide to buy it.
I think offering demos would be awesome. A good way for people to test a game before committing to it.