Err....maybe by working like rest, becoming independent financially, in a better position both financially and mentally to take the most important decision of their lives. I m amazed how could someone (regardless of Indian or Pakistan or Bng) even oppose such decision.
And to your 2nd point. Poverty is the main source for their background to be deprived. How exactly doesn't one improve their background ? by working, by earning. How will one work or earn if they will be married off by the time they finish their school ? That's why this legislation is brought.