DM is 55, so not old at all.
We've just been out to do the weekly shop we being me, DM, my GFather (84) and my DD (2). I can drive, and do drive regularly but not insured on DMs car but I do have a car I share with DH who has taken it to work today. My GF drove until a few years ago when he surrendered his license due to medical issues.
It's quite windy here today, I could feel the wind underneath the car was quite scared the car toppling as we approached a roundabout DM sped up, I asked her to slow down as there were no other cars on the roundabout and it felt like the car was tilting slightly. DM apparently didn't hear me!
She then walked off from me, DD and GF with GFs walking stick when waiting in the post office queue, I was holding two bulky parcels one of which was DMs!! ready to send and was hold DDs hand so couldn't help GF too. Thankfully a lovely lady in front took him by the arm and walked with him to a chair nearby, then came back and held onto my DDs hand while I waited to get to the front of the queue. Apparently my DM thought she'd told us she was popping to the town hall across the road to have a look at the car boot sale going on 
Then in Tesco, DD in the trolley seat, DM pushing the trolley, me holding onto GF and he had his stick again now too, DM walks off with the trolley while GF and I are waiting to get something off the deli counter. Spend the next 10 minutes looking for her, as she's not answering her phone. When we finally found her and DD, DM had finished her shopping and apparently didn't have time to let GF and me finish ours.
And then DM sits out in the car with GF while I rush round trying to get both mine and GFs shopping with DD getting more and more fraught before DM drives off without me as she keeps threatening to do as she's on a "time limit", a perceived time limit she sets herself to get everything done, forgetting that she has her 84 year old father and a disabled 2 year old in tow.
AIBU to think my DM is in a dreamland most of the time and to never let her leave the house again?
And yes this is lighthearted, she's a great DM most of the time, and wouldn't really drive off and leave me as she knows that it would leave me stranded she just puts so much pressure on herself to do things "right" that she often ends up rushing.