How can you sell a piece of yourself? After all, trafficking in people is illegal. So why is it allowed to sell unborn children yet? In addition, a woman bearing a child is inflicted enormous harm to her body which is not worth any money. In addition, such children will be weak and more likely to get sick. This is a very dirty business.
There is no evidence to prove that surrogacy is harmful either for the mother or the baby. Most of the babies are healthy and they face no long-term health complications. And in countries where the average salary is like $1,000 per year, a one time payment of $20,000 or $25,000 can go a long way in eradicating poverty.
There are negative effects, it is simply not profitable to spread information about them. In the first place, there is a psychological trauma of a mother's break with a child. At the physical level, the implantation of foreign embryos in the mother's body also has a negative effect and very often these rudiments can not take root in a foreign organism. In addition, this affects karma not in the best way. The economy needs to be improved in other ways, and not by this dirty business.
You can talk like this because most probably you hail from a developed nation and you can find a job quite easily. But think about those uneducated women in the third world countries. Most of the times, they have very few choices to earn a living. And for them, surrogacy is a better option when compared to prostitution and robbery.