You might be interested to hear that Juniors are the group most likely to be deterred by the sample. The (great) majority of candidates have backgrounds and capabilities up to or exceeding what we're asking them to do. We actually get very few under-qualified applicants.
The process appeals to people who appreciate a fair and objective approach to hiring as it demonstrates how we value those traits. We "set the tone" early by giving everyone an open and honest shake at proving their abilities, without the awkwardness of dealing with a biased human filter.
I don't agree with the premise of your salary comparison.
The process is willing to pass on candidates and wish them well if they aren't willing to take a test -- again, if it would be so "beneath" their skill and experience, that's a spooky indicator of attitude.