You make the ludicrous assertion that you *won't* be paying for that child's birth and all the medical costs of its ENTIRE LIFE. Not to mention as I stated earlier, the likely broken home from an unwanted child leading to governmental intervening such as court dates, adoption procedures, orphanage subsidiaries, and all the other costs that the taxes you already pay front the bill for.
You say that 600 dollars isn't that difficult for anyone to acquire in the 90 days you have to get the abortion from date of conception. I wonder how many people know they're pregnant on day 1, oh wait, that's next to 0. Especially if they had relied on contraception, via birth control and/or condoms, one wouldn't expect the initial warning signs to be pregnancy. It's not even medically reliable to check for pregnancy for the first two weeks after conception. So that cuts your 90 days down to a *minimum* of 76 days. Add in that it's usually very unexpected and played off as flu symptoms at first, that cuts that down to probably 30 days. And if you wanna say "oh but they missed their period shouldn't that give it away?", a lot of birth control options give months without menstruation either by design or hormone changes in the body.
Given that an overwhelming amount of Americans outside of trust fund land are living paycheck to paycheck, making ends meet with pennies to spare, that 600 dollars becomes mighty hard to come by. Now also remember that a large portion of abortions fall under teen pregnancies, who may not be able to work at all. I guess the argument is "why don't their parents pay?" and it's a sound one. They would be, with taxes or insurance premiums. Most parents I know don't have 600 dollars ready for when Susie spreads her legs one too many times.
Then the question arises, what happens if they can't get that 600 dollars up in time? Do they push Susie down the stairs and hope? Do they pay the thousands of dollars it costs to have a baby, only to give it up for adoption and have it enter the government funded system? Gee, that seems efficient for tax dollars.
But I guess in your world, everyone should be required to have a savings of at least 300 dollars (two people, split evenly) in a special bank account called "Unwanted pregnancy relief fund" before they pass their "you can have sex now" licensing exam.