Calling something crap doesn't encourage constructive discourse if you're looking to actually gain something from a discussion. But I can ignore that.

The ballots are proposed as labeled "no support" to "most support".

It isn't entirely unlike Amazon, it's like Amazon if your standard for what's a 5, like "the best book" is "the best of THESE candidates". All people need to do to get the system is care about their impact on the outcome of the election in order to realize that 5 doesn't mean "love" or some other semantic thing, it just means the top of the options.

And if people just use it like Amazon and some give no candidate a 5, the system doesn't fall apart, it works pretty well anyway.

Is there evidence from real world trials that everyday voters do use STAR correctly? How many people use the full 1-5 (0-5?) range in their ballots?

STAR has never been used in a public election. At some point, we can't both argue about lack of evidence and against getting the evidence.

http://star.vote is not a controlled scientific survey or anything, but people overall seem to have no trouble using the full range.

In fact, in my anecdotal experience, even over years in the past when I told people about plain score voting and tried to get them not to use the full range (because I misunderstood that issue myself), many people insisted that they would use the full range anyway. A lot of people find it intuitive to give their favorite all the points they can.

But the real answer is that, yes, we need more studies and trials of all these things.