Yes, those texts exist. But as you said so does the logistics of buying and selling slaves. Revisionism hasn't caught up to LGBT subjects, because the majority of Christians are still bigoted towards the gay community. The community at large gloss over sins that they commit all the while discriminating against disenfranchised groups who 'commit sin' in their mind.

Here's an example I witnessed when I went to church:

A well known person in my old church beat his kids and his wife. Nothing happened. The obviously gay kid comes out and his whole family left the church through social pressure. The gossips (considered a sin) ripped their reputation apart. They effectively were churchless, because it was made known no family would let them attend.

All these things are considered sins: domestic abuse, homosexuality, gossiping. All sins are equal according to most denominations. One was disproportionately punished because the Christians who did that are bigoted, not just because their texts told them to, but because they are.