Well, last time we did bring carseats, but only when we took private vans for the entire day. And even then it was a total waste as the seatbelts didn't pull out to lock and we didn't have a locking clip for the seats, so basically useless. For a taxi I wouldn't even bother. In fact, we'll likely do some private vans again and not bring anything for our 3yo. I would like to, so maybe our backless booster, but she's super tiny (22lbs at 34" at 2yo), so she won't technically meet the reqs for our backless booster. Mind you, I am one of those, and I hate the term, "car seat nazis" at home. My 2yo is rearfacing, 5.5yo in a 5pt harness, and ~8yo just moved from harness to booster in November. So for me this is huge! But it was just such a waste of manpower last time with seatbelts that didn't work with carseats that I figure why bother? So we'll see with the backless booster, but that would be the extent, and only if I can leave it in one van all day, not carry it around cause *that* isn't happening with 3 kids to watch!