There has never been a time when I needed a pregnancy test (to determine or rule out) that I didn't head straight to pick one up. I have never gone to the store for the test and forgotten to buy it, if indeed I thought I should use one.
So forgive me if I had to ask the cashier at Walgreens why in the world would there be a pregnancy test on the shelf next to the check out where they keep the impulse buys. It wasn't placed there by someone chickening out, either. There was actually a price on the shelf.
I know that people frequently buy the things that are put there. I can't tell you how many times I have been waiting in line to check out, saw something I needed, and picked it up right there. They actually do lots of research to determine what items sell best next to the register. But who goes, "Gee, I totally forgot I needed a pregnancy test. Good thing they put it here!"
And in answer to your question, I did NOT forget to buy one this time, either.
I didn't need one.