The answer is: Both measures rob a developing nation of money it could use to invest in social welfare improvements.
Both structural adjustment and funding for social welfare come from the same government budget that collected through tax payments and other government revenue. (this mean that if the budget is used for structural adjustment, the budget for welfare would be reduced and vice versa)
For developing nations, structural adjustment often could not become a worthwhile investment since the countries need to improve the quality of their labors first in order to generate productions in their nations. This could only be achieved by investing in social welfare.
