I've been asking that question for years.
A 's0lid on one side, blinking on the other' setup is going to be perceived as a turn signal 'cause that's pretty automatic, regardless of what vehicle is between the lights.
At night, it's a little hard to see my hands.
I can see how when I'm lit up like a Christmas Tree then it's gonna be hard to see a signal... andg enerally I penetrate the "automatic" systems then and people are looking hard enough to see a hand (given the CHristmas Tree effect).
The $7 one probably isn't going to make it through one of my winters. Stuff that cheap is generally... cheap. I'm careful, but I use things and stuff gets bashed around a bit.
IMO, with the recent developments in LEDs, this is a brainchild waiting to happen.