so why is birth control bad to fund?

things still make no sense

I can realize that we're not about to pass some sort of law funding abortions for low-income families. But wouldn't it make sense to expand birth control to counter that demand? Secondly, sex is a pretty cheap form of entertainment for married couples especially (meaning having more of it might be encouraged in a low income environment brought on by temporary unemployment). It might not stimulate the economy to spend on child prevention, but it will SAVE money by lowering the societal costs of unplanned/unwanted pregnancies.

Yet somehow what is a voluntarily available provision: birth control subsidies for the unemployed/poor, is interpreted by the public media as something like an involuntary birth control policy limiting child births?

There's some logic to the social security argument to have more people paying in to support it against the number of people drawing down on it...but that assumes that young people are all that excited about essentially subsidizing the retirement of their grandfathers while still receiving no guarantees their own money will be there later when they will be owed it back. Which I'm not personally all that happy about this possibility. And I doubt a child much younger than I will be all that excited either when they don't even pay into it at all right now. And it still doesn't actually save us any money to look at this situation of the young supporting the old involuntarily as good and self-sustainable.

My only objection to such funding would center more on libertarian grounds at the federal level (ie, do we actually have any constitutional authority to do that?). I can easily recognize some fundamentally useful economic grounds to having children be more of an economically tied resource than they are at present and where the incentives for not having children are just as obvious as the economic incentives to do so (this is the present case for people who are perceived as totally fucked in the socioeconomic scale that having children is a positive gain versus doing anything like family planning). We as a society should probably figure out ways to correct for this error of logic as it increases our costs of education, criminal detention, and subsidized health care costs for the poor. It is obviously a lot cheaper to prevent a child from being conceived than it is to have one, just as it is cheaper to discourage people from continuing in tobacco addictions through treatments then as it is to treat cancers or other diseases brought on by long-term use. If we're going to pay for these things in a social way, through our taxes, then it would make sense to have some obvious cost controlling incentives built into the programs.