Prices seem fine, in line with other consoles digital stores. Considering the increased cost to Google of free unlimited streaming this is good.
Saying you can get X game much cheaper on X platform is always going to look very negative to new releases. An example would be Witcher 3 that came to Switch for $60 when you could get it for $15 on other platforms. It's not exactly a fair comparison.
Nobody should be paying those prices though. All of those games can be had for way less money, either by waiting for a sale or buying a gently used retail copy. Digital storefront prices work like clothing prices in department stores. They always list the price as something ridiculous in the hopes that some sucker will pay it. Then when they are ready to actually start selling product they list a more reasonable price and call it "a sale".
Steam, PSN, and XBOX stores all work because there are alternatives for customers to shop at for a fair price. If you don't like the prices on Steam's main page you can always just buy a Steam Key from another web site at a fairer price. If you don't like the prices on PSN or XBOX you can always just find a physical copy for less.
But what can a Stadia customer do if they don't like the prices listed? Nothing. Publishers want it this way, and like it this way. They want to be able to charge the maximum amount for their product. And in an ecosystem like Stadia where there's no competition for game prices, they can indeed charge whatever they want.