There could be a number of reasons like the ones already stated in the last 2 comments
Locals don't always feel the need to go green due to the costs but if their numbers are showing then give them a go
Mondays does appear to be a change over day, i was on the King's Cross to Doncaster train this morning and it was full of chinese/asian women, others too, I felt like a kid in a sweet shop, only issue was I had my lad with me...

so I dare not risk instigating any conversations