Slavery Is Not a Good Way of Translating the Hebrew Concept

Exodus 21 2 says if you buy a Hebrew servant and again I would say this is not he's not buying it's a financial transaction that involves paying off a debt in exchange for labor. In the seventh year he shall go free without paying anything so there's a time limit on how long you can be an indentured servant doesn't matter how big your debt is six years and you're you get a clean slate to go home. When we get down to verse 7 it reads if a man sells his daughter as a servant she is not to go free as male servants do  this sounds really troubling why would a woman not be allowed to go free if a man is allowed to go