I actually did ask that once. They can't, because it's not permitted to pay people to donate (in money or for-like things like Vitality points). I guess the biscuits, juice, and SANBS gifts are allowed though.
I'm a universal donor - Oneg - and I used to donate blood until I had a bad experience with a nurse who was angry with another nurse in the clinic and decided that was the perfect time to take my blood. She stabbed the needle in my arm and wiggled it around because she couldn't find the vein. If I could've unclenched my teeth and fingers from the pain I would've said/done something.
I can only imagine, the last donation i did the nurse did something different to past donations and it was somewhat painful / rather uncomfortable to even move with the needle in, i mentioned it but said I would just grin and bare it. I wouldn't want to repeat that experience nevermind something worse!
I donated when I could when I was at school, since they'd visit there once every term, but I haven't since. I mostly did it 'cause you could skip most of the day's classes by donating (or saying that you're going to donate ).
like @Defib said Nonsense
look dude if you don't want to donate don't donate it doesn't make you a coward its a free choice i disagree but respect it., making up BS excuses that makes you a coward
they ask what medication and if on the allowed list, they take your blood, if its like aspirin they take certain parts of the blood only if not on the allowed list they don't take.
I'm on BP meds and they take my blood i just advise them what Im on and if i recall the only thing is you must be on that medication for at least 4 week funnily enough the reason i picked up an issue with my Bp was cause of my blood donations.