From a business perspective, letting merchandise sit at a warehouse while waiting for something is non-productive and costly.
Just storage costs a certain amount of money, but worse, there's a lot of money that was spent on procuring that merchandise, money that is likely borrowed and losing interest, but even if it isn't borrowed, it is money that is expected to return even more money.
A business would like to turn over merchandise as many times as possible in a given year, because every turnover is profit.
The math is quite likely that what ever losses happen due to customers receiving items that turn out to have bad tests, and having reshipments and reputation loss, is far outweighed by the gains of having inventory turn over more times than it otherwise would.