They should do chores because it's part of being in a family.
My dc's don't get pocket money yet but have chores to do. All my dc's from the 4 year old to 9 year old have to put their clothes/towels in the wash basket, pick up their own toys, put coats and shoes away, do homework, help load the dryer every so often, take their plates to the sink and put clean towels away.
From about 5 they've had to put their clean folded clothes away, make their beds (or at least try), tidy their rooms so I can clean and vacuum.
My 8 and 9 year old sweep the wood floor, (try to) dust, help hang washing out to dry, occasionally make their lunch for school, hang school clothes in the wardrobe, get their own/younger siblings school clothes out of their wardrobes, help put shopping away and they're starting to help prep dinner once in a while.
13 and 15 year old should be helping out at home regardless of pocket money.
I wouldn't link chores to pocket money because they should be doing them anyway. Essentially paying them for chores ends up with them doing nothing, especially if you give them money for going out with friends anyway.
I'd be stopping pocket money, no extra money to go out with friends, no WiFi and no going out until chores were done. It's harsh but they just sound lazy and spoilt.
Who cares if their friends don't have to do chores? They have to so they can lump it. A friend of mine is married to a man who's mum used to do everything for him, now he expects my friend to take over and it's driving her nuts. I'd be ashamed if my boys grew up to be like that.