The “an AirTag is traveling with you” alerts haven’t been defeated as far as I can tell. Apple tweaked some of the time periods after launch but the core technical mitigations are the same.
I agree the current situation is non-ideal, but it’s not clear to me this is from a lack of sufficient pre-release pentesting.
Perhaps not, but they're meaningless to the >50% of the population that doesn't have a modern enough iPhone as their daily carry phone.
Having moved back to a flip phone, I literally have no way to identify if such a tag is being used against me.
A quick look on Amazon UK suggests that there are plenty of cheaper options and, whilst not many, there are options of a similar size to the AirTags.
Now, admittedly, none of them have the same feature set as an AirTag but if you're at the point of buying GPS trackers to stalk someone, I doubt you're thinking about the technical distinctions.