On car park as I type. Family next to my car just got back. Little girl just had wee on floor behind and between both cars (I was just getting out and the dangly bits of my sling nearly went in it).
AIBU To think that you would carry around potty, jar or tub for this purpose when your child was this age (under 4ish).
I might be U because I have a baby so have no experience of this stage. Also it is the hospital car park I am thinking they might be stressed from visiting an ill relative.
but... there are toilets next to us in the building on one side, and also a wide vergey bit with trees and a wall - in this situation I would use the verge or a tub.
I am posting from interest really to see what people would do ready for when my dc reach this stage!