They do, however don't expect Air Canada flight attendants to be wandering up and down the aisle looking to see if you want another drink.
They want to get you on, get into the air, give you a meal, give you a drink, clear the trays, sit down for 7 hours to read, sleep, complain about the company they work for, then give you a little sandwich and a water before landing.
If you do see an flight attendant walking through economy class on a long flight it is with a purpose. They put their heads down, get a scowl, build up a head of steam and rocket through economy so quickly it's a wonder Canada doesn't win Gold, Silver and Bronze every Olympic Games in that 'Race Walking' competition. They will do all this while refusing to make any eye contact and pretending not to hear any customers requests.
Get an aisle seat and wander back to where they all hide from the customers, then you will get a drink.