Had this occurrence 3 times in Europe, once the car park attendant passed me the ticket/token, other 2 times I just had to get out of the car, grab the ticket, and get back in, raising my hand briefly in apology to anyone waiting behind me. Suspect it added 20 seconds on the way in and the same on the way out. Wasn't a huge annoyance.I drive on my own most of the time in UK other than weekends and park my car in parking lots a lot. The ticket barriers will be on the wrong side to insert the ticket to open barriers - LHD x/s is going to be practically difficult for me when I am living 90% of time in UK.
Many of the car parks I did encounter were using number plate recognition, so no need to collect a ticket on the way in or to submit the ticket to the machine on the way out. If this becomes more common place then the only disadvantage remaining for me personally would be visibility when overtaking on single carriageways.