Please explain why taxpayer funds should be funding people who live in this country illegally. To state that it is a bumperstickerism without providing an explanation for why this is so is an ad hominem attack.
The Federal government is also notoriously lax on prosecuting employers who use undocumented workers. Can you explain why:
a) the Fed withholding funds from California somehow "because" they have spent money supporting illegal aliens is somehow different from:
b) California wanting to withhold funding from the Fed because of their relative disinterest in prosecuting those who knowingly employ undocumented workers (thus exacerbating, if not indirectly causing situation A in the first place)?
I'll assume you are sincere, and write an answer. There are a few reasons I can think of.
1. They (people who live in this country illegally) and their families are often also taxpayers, so... why shouldn't they benefit?
2. It helps promote social stability and harmony.
3. It offers stable households for children growing up in their families.
4. It's the humane way to run a society. It makes our society more humane and less mean spirited, and thus better not just for them, but for the rest of us as well. Maybe this looks like a restatement of #2 but if you think about it, #2 follows from this one. Many of the points follow from each other. For example, the next one:
5. It arguably reduces the types of crimes that emerge when people are in desperate circumstances, which can include theft, burglary, violence, extortion, scamming, and others.
6. It increases public safety, for example if they can get driver licenses, then the existing system which gives everybody an incentive to learn and follow traffic rules will also apply to them, without the extra costs that would be incurred were we to deal with them as extraordinary cases using some other special system.