Faffing about.

If I have specifically been asked to give my friend/neighbour a lift to and from an appointment, that would be my only mission. Once I have dropped her back, I would carry on with the rest of my errands. But then I don't know what distances are involved here.

Distance could be relevant. True...

And if someone I was with spent twenty five minutes in the bank I would probably suggest Internet banking in case they hadn't thought of it and might be glad to know
That would be very patronising and given the timing, extremely obvious.
The word entitled springs to mind

Basically, if you want to call the shots, use a taxi another time.
I think the criticism of her driving was however the lowest part of what was effectively a good old moan,

You're not going to let this go are you Maw? It was a light hearted moan, friend didn't notice I was vexed as I am too polite to let it show or openly criticise her driving.

I was mainly taking issue with Annep1 who clearly thinks all you say is justified.
Perhaps it was a light hearted moan, if so I am sorry that I, along with others, took you seriously.

I will however be very careful about my standards of driving, punctuality and absence of “faffing” whenever I give lifts to friends who no longer drive.

I think YABU .
When i grumbled to FiL recently that there was hospital transport so he didn't need me every time as a taxi for his op appointments, he had the cheek to tell me it was too slow!
I guess he's family so I have to drive but if he dares to criticise my driving. Grrr.....
In the days when he could drive, did he ever offer lifts? Ask yourself Kircubbin would you have done the same for her?

For the last six months I have had to rely on my family for lifts to medical appointments, some early in the morning or a distance away, I would never dream of criticising them if they tried to fit in some chores around the visits.
I'm just so grateful to get a lift and that they have given up their valuable time to take me.
Even if it was a lighthearted moan, take a taxi in future, if you have problems with your friend's standard of driving.
I think you are very lucky to have a friend who cares enough to take you.
If it had been me, I would have taken the opportunity to go into Lidl with her and stock up!!
My very comfortably off son, used to turn his nose up at Lidl until he tried it. He is one of their best customers now!

My Sis-IL tells me that there is a 'friends' group which offers a car service for patients at her local surgery. Since she gave up driving, she has been very grateful for its services.

On another point - how to suggest to a friend that she should perhaps relinquish her driving licence?
I expect short shrift if I do say anything.