So I landed in Paris. Already ran into some awkwardness at the airport. So as in other cities (especially around New York), there are official Taxis and random guys that grab you before you get to the taxis. I was semiconscious of this, but also found myself unwittingly giving the guy attention and not wanting to be rude. I also did not see the official taxis anywhere, so I thought perhaps something was different here. I began to regret not just walking past him when it was clear he wasn't just parked outside, but was talking me elsewhere. It turns out, to the parking garage. I was on guard, but didn't really know how to break away from this gracefully.
When we get to his parked car, he my luggage in his trunk and says he'll pull out so that I can get in the passenger's seat (the front seat; which was too close to a wall to enter). Well, at this point my luggage was in his trunk, and I began thinking maybe his thing was to just drive away while he was pulling out and steal whatever was in the trunk, or something. So I got in the back seat. He was insistent that the front seat was more comfortable with more room, and I insisted that I was okay in the back. (Also, you always get in the back in cabs.) He then showed me his taxi license, saying that it was "very important". (Red flag #47525, but recall by this time I was somewhat committed as he had one of my bags. For what it's worth, the license looked legitimate enough, but how would I know?) He kept on saying I should go in the front seat, and he stopped before the exit turnstile and wouldn't proceed without me moving to the front seat. Finally I said that I want my bag and want to get out, and he was actually amiable enough. So I got my bag and went back and found the official taxis.
I think the most likely scenario was that it is illegal for unofficial taxis to pick up people from the airport. (NYC has a law like that, I believe.) So if the police saw me in the back seat, it would be fairly obvious I was a fared passenger, and he could get cited. The possibility that he was going to steal from me or kidnap me in some way was less likely, but it was still in my mind.
When I got in the normal taxi, I tried to ask the taxidriver about it, and showed him the business card the other guy gave me, but he did not speak any English, and I only know enough French to converse on the level of a particularly slow three-year old, so I couldn't make him understand. Anyway, I made it to the hotel, napped/passed out, and now I'm ready to go explore~