I am step parent to an adult DC who doesnt drive. It is not due to a lack of support - paid for theory, gave money towards lessons, even gave a car. They stalled (pardon the pun) and have paid for years to insure cars without having passed for various reasons. So it isnt always fair to suggest children who drive late is due to the parents.
I do get irked that this means more running around on our part - and I would feel exactly the same if my own DC I can assure you.
All that said, I wouldn't expect my partner to not see my SC on xmas day if the opportunity presented itself. Usually because of the distance we alternate but it is further than a 3hr round trip. If it was only 1.5 hrs each way - which some people commute to work, to be fair - I would support my husband in doing that. I would want to see my SC too.
I wouldn't feel sad about being left alone on xmas day because I would go in the car with them and play xmas songs and make hot chocolates for us for the journey, if I am honest.
I wouldn't agree (and yes I have a say as we make decisions together) to driving late in the day as it would interfere with dinner and xmas drinks. However midday is, I think, reasonable. You'll be back for about 330pm. If pre xmas dinner prep is done before the drive, it wont take long to finish for an early dinner. I would be happy to eat later than usual (if it is later for you) to accommodate that to be honest.
I would have the option of staying in the house on my own for 3 hours if I didnt want to do the drive and would probably use it sorting stuff out for dinner/evening plans and having a relaxing bath. I appreciate not everyone feels that is a good use of time but I would be cooking anyway if husband was there as I usually do (I enjoy it) so it doesnt actually make a massive amount of difference if he is milling around helping or not.