To
@Mike Schramm's point, which I somehow missed when I was responding, exactly.
The initial digital window is generally at a higher price point. Sometimes rental only. "PREMIUM RENTAL" or "STILL IN THEATERS" type hype. These vary from studio to studio, sometimes they're purchase only, sometimes they're rental only, sometimes they're either at a higher price point. Rental on Kaleidescape during this window is generally $19.99. When physical media is released, the rental drops to the normal $7.99 and purchase price drops to where it will eventually stay.
Though that being said, Paramount has been fantastic. The Top Gun Maverick pre-order was $24.99 to buy and it stayed there for quite some time. I believe it's down to $19.99/$7.99 now, with occasional sales dropping lower.
Personally I will tend to only buy during this window, and I'm happy to do it. If it's a title I only want to rent, it's also a title I'm fine with waiting for. I can't recall any movie I wanted to see badly enough to pay $20 to rent it.
Basically there's some set of formulas each studio has created where they think they're squeezing enough market segments enough to maximize profits while not squeezing so hard they...ahem...blow the bottom out of their markets. How accurate those formulas and perceptions are is still TBD. Warner seems to be popping heads with their price squeezing, though they also seem to be purposely making poor financial decisions in all areas of their business. They've been pricing their marquee titles at $39.99 to purchase on Kaleidescape, which means I am very picky about what I buy. Disney and Paramount have found the automatic price point at $24.99. If it's something I want to watch I'll hit purchase without even thinking twice.
If you compare Kaleidescape pricing to iTunes, you'll generally see a $5 upcharge for Kaleidescape titles, which I see as fair enough - they're offering more. Warner, however, has a $15-20 upcharge on Kaleidescape, which is not justified in most cases. Even for some catalog titles, they're still wildly overpriced.