Paying for bus tickets with notes, why is it such a crime?

Admittedly, I HATE doing this, and of-course will avoid it at all costs, but every now and then, it is simply unavoidable. obviously I'm not talking about a 20 pound note for a small bus fare, but on a couple of occasions I've only had a ten pound note, just yesterday, i was about to leave the house, when i realised all i had was �10 for a �3.10 fare, i ran to the main street, only to discover a large que in the fruit shop, the only place close enough to buy something and get change. Normally i would wait in the que and get the next bus, but yesterday that would have made me about 15 minuets late for work, i then walked quickly to the bus stop, got on the bus, and decided to ask for a �4.00 all day ticket, to which i had need for, to save him 90 pence worth of bother, and then sincerely apologized for having nothing smaller, quickly explaining the que was too big to get change, only to be told " why should you be any different for the rest of them! and just for that you can have your change in coins!" accompanied with a look of disgust. i don't mind getting the change in pound coins, but was there really any need to speak to me like that? i always try to avoid paying with a note, but sometimes its just unavoidable. Why are some so grumpy? i get some wonderful bus drivers sometimes and it starts/ends my day in a nice way! i understand they get trouble of the public, but so does anyone who works with the public, i serve coffee in a train station, often working by myself, and you wouldn't believe the amount of angry businessmen or stressed traverlers saying obscene things to me because they're about to miss their train because its took more than five seconds to make their drink, but i still keep a smile, i don't take it out on the next innocent person!