Cult of the Lamb is $24.99 on Steam
Unreal royalty is 5%, so $1.25 per sale
Unity is $0.20
So royalty is ~6x more
If there was a reasonable way to count installs (I don't think it is technically possible), install fee is much better than royalty for most devs who are not F2P apps.
Let's say I really like this game and install it on my laptop, desktop, and steamdeck (3 installs). Now, let's say I upgrade from win10 to win11 (4 cummulative installs). Alright, now I'm bored of the game an uninstall it. A year later the game recieved a new free DLC including new content. So, I install on my laptop, desktop, and steamdeck again, after I have updated both PCs from win10 to win11 or made some other hardware change (7 cummulative installs). And repeat this process every 2 years.
Unity's price is now much more than Unreals as I'm now costing the dev $1.40 after just the first update. Every subsequent update means I'm costing the dev another $0.60.
This may seem ridiculous, but anecdotally, it seems relatively common.
Again, the issue is not with Unity wanting to make more money, but with how they are trying to achieve this. Install based cost means you cannot estimate tooling cost as it is impossible to estimate situations like above.
https://isthereanydeal.com/game/cultoflamb/info/
For Slay The Spire I paid $8.49
https://isthereanydeal.com/game/slayspire/info/
This also ignores regional pricing differences. Games tend to be cheaper in the India/Brazil/etc regions on Steam
And if a user installs a game twice, do they have to pay the fee twice? Forget review bombing, now people can hate install a game.