I drive Uber part time and people stay getting in the front of my ride, solo or not. It weirded me out at first but now I just be like whatever. I still don't kind of get it b/c half of em don't even talk, they just be on their phones while the rides I get where people are in the back do more talking than solo front rides. Uber just makes mafukkas way too comfortable I think. Nobody was ever out here sitting in the front of Taxis like that unless it was more than 3 people. People just jump in the front too. It ain't even a matter of asking. I'll occasionally get the "do you mind if I sit in the front or back" but most of the times they get in where they fit in.
I get what you are saying, but it is human nature to sit in the front. shyt becomes formal if they sit in the back and there is only one of them. Some driving Miss Daisy shyt and you are their chauffeur. I have sat in front of a taxi before, especially when there are 3 people. Usually the driver is like "you want to sit in the front"? It is no big deal.