[RedDevil]

It is not in the unicorn corral because these clips are used by several car companies and their function is well understood.
Honda puts 2 clips on each front brake of a Civic and 1 on the 2nd gen Insights.
It is no snake oil.

They solve a problem that should not be there in the first place.
When you apply the brakes the fluid pushes the pistons against the brake pads, which make contact with the disk and slow it down by friction.
When you release the brakes the brake fluid recedes and pulls the pistons back in. But the pads stay where they are; against the disk. If the pads slide freely to and fro the disk that is no problem, as the slightest touch against the disk will make them move back. But often they do not move that freely and keep stuck against the disk, heating and prematurely wearing themselves.

The springs put a relatively minor force on the pads to make them stay in contact with the pistons. Once there the brake fluid prevents further regression.
There is no such thing as pushing back the master cylinder and needing to pump before they can be fully applied. If that were so the system would be leaking, and leaking badly as the force on the brakes when applied is so much greater than the spring action.

What makes it hard to quantify the effectiveness is that the excess friction on brakes without them is not constant. It will be there after breaking, but recede over time as stresses on the axle and bumps in the road allow the pads to move back. Nonetheless there are statistics and they unmistakenly show the effectiveness of the springs.

The same erratic behaviour of brakes that miss these springs can be felt in a stock Insight, like mine was, when you gently brake to a stop. At first it will use only regenerative braking, but as the speed gets too low for that the disk brakes will apply.
The transition between those two phases was always a bit unpredictable; suddenly breaking harder one time, while hardly braking at all the next time.
Although that behaviour is not yet completely gone, it is much less annoying than without the extra springs. I'm in control instead of on edge.

When I had them mounted we turned the hubs by hand. That was hard without them and noticeably easier once they were on.
Now when I put my car in neutral I can push it forth and back with two fingers. I did just that a week ago.