A key factor here should be the complexity of the agreement compared to the value of the transaction.
If you're buying a house, you're laying out at least six figures and can be reasonably expected to read the fine print or hire somebody to do it for you, even if it takes multiple hours or several hundred dollars. If you're buying a $1 app or using a free service, expecting the same thing is facially absurd.
Meanwhile if you're buying a $5 bottle of drain cleaner, it's ridiculous to expect someone to read 20 pages, but 20 words is not so unreasonable.
This also bodes ill for "we may update this agreement at any time" because that's imposing the burden of re-reading the agreement every time you change it, which is pretty unreasonable for anything where the other party isn't paying you (or getting paid by you) hundreds or thousands of dollars a year.