you're thinking in terms of "business rental". you're not considering a one-day one-way rideshare - which happens to be common (albeit not in your universe per se). This is a significant step up to picking up a hitchhiker: you post on rideshare board, and have (in this case) dozens of conversations/recorded texts/emails with a person over a number of days. Then both go to rental counter and hand licenses over. Very far cry from hitchhiking. Nothing wrong here whatsoever.

And again, the entire experience was (as usual) very positive and truly enjoyable. No surprise there at all, as has been done and repeated scores of times since the student years. I'm surprised people insist on being close-minded about this. Life is not just about business dealings, there is a lot of informal interaction in a normal person's life. And a lot of sincere and mutual helpfulness to everyone's benefit. But here is a case where it's hard to get help from Hertz (and I'm not at all saying they owe it)