Why is a stock that trades below $1 USD still listed on the NASDAQ?

Companies can delay, delay, and further delay being delisted from the Nasdaq by offering promises that they cannot necessarily keep.

They also can optionally reverse split, indefinitely, to make their share prices trade at a higher price. So, one press release saying that they will or MAY reverse split, and Nasdaq will keep them listed. After the company exhausts it's lies and promises, then it will be delisted.

Some companies continue to trade because they meet overall market cap requirements or some other factor(s) which allow them to continue to trade. Share price alone is not the determining factor, ALTHOUGH it is a large one.