Yes been asked to pick clients up some do do this I hear but not me not on a time or insurance invalidating basis. Plus my car is my personal space, I'm quite funny about it with friends and family!
One punter directing me into a very rural location just jumped in, also had that arriving at a lodge park. I often have a bag on the passenger seat.

. I use the door locks more and more, especially after a man tried to get in my car as I parked after getting back from a booking thinking I was a taxi. He was drunk, it was really scary (luckily locks on so he couldn't but he was pulling at the door handle). My car looks nothing like a taxi

Ten minutes after I thought "I was more at risk then than in a booking with a punter"! (meant in the best way).
Sheesh.