You would be surprised (or maybe you wouldn't) at how many applicants get filtered by extremely basic elements of a tech test that's specific to the employer and therefore not something that can just be memorised or drilled. It's a low bar, but it can be a very worthwhile one.
There's a second factor, too, which is that sometimes you want an easy test so that you can judge coding style. You need to be careful not to ding people who don't already use whatever your house style is (which has bitten me in the past) but you generally do want to see something that you can have a style conversation about.
There's a second factor, too, which is that sometimes you want an easy test so that you can judge coding style. You need to be careful not to ding people who don't already use whatever your house style is (which has bitten me in the past) but you generally do want to see something that you can have a style conversation about.