If you take your parents/in laws to medical appointments or to ONE shop, do they add on extra shops/banks etc? I'd potentially be more flexible if MIL actually asked, or had no other support, rather than just saying 'Oh and I need to go to the bank, and then I need to pop into Sainsburys and then....'. MIL does drive, can order all manner of crap stuff online herself, but refuses to do internet banking. Her mobility isn't great, so being driven means she can be dropped near the entrance- because she refuses to consider a disabled badge.
DH and I work full time and live a distance away. SIL works part time and lives 2min from MIL, but MIL doesn't want to bother her or BIL! And yes, we are saying no to added stops. Sorry, I just needed a rant!