The only time I've had 'problems' using public transport in a kilt was about ten years ago in a rental.
My colleague who was going to the event with me, is a burly Scot - broad at the shoulder, large beard, the works, and was wearing a leather kilt, with targe and peace bound claymore (I'd taken the forethought to warn the local police), and when we came around the corner of the tube station we ran in to a group of Japanese tourists. Half the women took fright at seeing a 6ft, kilted, bearded, hairy legged, BIG guy strolling with a huge sword through the station.
Mind you Dave was a bit scary even in plain clothes.

Needless to say after reassuring them that we weren't about to start Bannock Burn again, we spent the next 20-30 minutes having our vision turned into purple rectangles - 'jus one mor photo prease!'...