What do you think of people who disgard their pets?

I do volunteer work at various animal shelters. There are too many ex-pets in those shelters. A lot of people receive pets as gifts. Instead of telling the gifter that they don’t want a pet or are unable to look after a pet, the recipient usually just dumps them and they end up in a shelter before being euthenased. Who do you think is more responsible for this sad end for the pets? The giver or the recipient? Also some people have had a pet for years. When the said animal gets sick and/or old and needs veterinary treatment they just abandon it at a shelter (or worse.) Something needs to be done about the 1000’s of innocent animals that are euthanased every year. Any suggestions?