Immigrant labour.
Not entirely of course, but some are remarkably course and it doesn't even register with them that they're in female company...let alone in public.
Before anyone goes off on one, its based on observation. Ive worked for the last 11 years in an industry where the vast majority of staff are immigrant labour, maybe 10/1.
My last employer had a lot of immigrant labour. We'd sit in the smoking shelter and there'd be 6 or 10 of them stood nearby, some of them frequently gobbing on the floor...while girls were sat a few feet away. Completely oblivious to what they were doing until Mary went red faced with anger and shouted 'FFS you dirty b'stard

' I think she'd been bottling it up and couldnt hold it in any longer (her anger not gob

)
Or put another way...plenty of us spit if bodily neccessary, but we do it while no-ones looking.
In all the years ive been working, i've very very rarely seen people spit...until we got immigrant labour. I see it now so much more regularly from them it hardly registers anymore.