Modern Christians may have come to accept the practice of charging interest to unbelievers who can afford it, because the Bible doesn't forbid it.
1 Corinthians 10 says Old Testament examples were also written for the
benefit of Christians. Leviticus 24 tells God's people they are not to take advantage
of "poor", fellow Israelites, by charging them interest or selling at a profit. It did not forbid charging interest to, or making a profit from sales to non-Israelites.
Acts 4:32 ff., sets an even higher standard. Christians were voluntarily selling
their possessions, to meet the needs of poor Christians, so there would be equality. No mention is made of Christians doing this for non-Christians.
The NT calls on Christians to "remember the poor" (Gal. 2:10).
The practice of lending with interest to unbelievers who can afford it, was not prohibited in the Bible.
As far as borrowing with interest,
Romans 13 says "Owe no man anything...". However, "owe" is in the present tense, not the perfect tense. Therefore, it doesn't necessarily mean never owe any man anything at any time, but may be interpreted as "don't keep on owing any man anything" (i.e. don't let your debts remain outstanding).
With that understanding, a person who pays their monthly rent on time, is not allowing their debt to remain outstanding, but is paying it when it is due.
We were actually paying as much in rent as we later paid in monthly mortgage, when purchasing a home. While Proverbs warns against becoming a slave to the lender, it was actually a better stewardship for us to take out a loan to buy a house (with interest), than it was to pay the same amount in rent, but without ownership or equity.
Christians may have come to accept the practice of borrowing with interest, because it can sometimes be better stewardship than paying rent.