Thats because such rates typically assume that the loans run for a long time. If the loan is only for 14 days the interest (given as %apy) quickly skyrocket.
You mean it is not a yearly interest, but a constant? Like "we give you 100$ if you promise to pay us back 170$ whenever you are ready"?
It is yearly interest, but the loan terms are typically much shorter. If the loan only lasts 14 days, a quoted APR seems much higher than is typical for, say, a mortgage, which lasts 30 years.
This makes some sense if making the transaction has a fixed cost. If I had to spend the same amount of time to fill out a 14 day loan as a multi-year one, I'd need to price the shorter one higher even if I wanted the same APR otherwise.
...but if the borrower is on the same thin financial ice when the loan is due as he or she was when the loan was taken out, and rolls the loan over, then things get out of hand very quickly. This is how the people offering paycheck-anticipation loans rack up their profits.