In all honesty its not just reptiles that animal control will make quick judgement to put down.. We took in a Very pregnant Very underweight dog who they were going to put down because they didn't have enough space for the puppies.. and it probly didnt help that she might have been the ugliest cute thing I have ever seen.. she looked like a gargoyle with fur (all 5 puppies and the mom found homes BTW :P)..
Unless a rescue is called then many animals won't stand a chance especially in government run facilities. Snakes are not a popular item at the pound and they take up space.. therefore its easier to just not care for or keep them.