Who is going to pay the parent a survivable wage? And how is that person going to get the money to pay them?

People are starving (well usually the problem is that they are very poor, not literally starving) because they don't have money, because they don't produce things of value that they can trade for money. Free trade gives people the opportunity to produce more value (e.g. by working in factories or producing cash crops) so that they can earn more money.