दक्षिणा

We are in the process of building our dream house. But we have observed that so many people ask money for small small works which they are already paid to do. For example: 1) People coming to drop off cement bags ask for some money as they unloaded the bags. They are already paid for it in the whole charge. 2) slab workers. Slab gang which fill the slab with concrete ask for 500-1000₹ as दक्षिणा(per slab). 3)Bricks unloading guys ask for money for unloading. But they are paid too.(For whole house work they might be called 6-7 times) 4) चौकट(door frame), this work is a bit special, so we do Pooja as this work starts. They ask for 1000-1500₹ as दक्षिणा. This isn't all. You may be asked to pay money anywhere you won't expect. Is this normal in this working field? What's your experience in such cases? Thoughts?