I've used these, I really don't think it's a big deal. maybe the ones I had were different, but again, they won't retract until you push down on the plunger well past the point at which it stops advancing. I get the whole not wanting to waste anything, but unless you flush it after injecting which of course you shouldn't do if you like your veins, it will always have at least a tiny amount still trapped in the needle itself, it's not going to be any noticeably more with these retractables.
IM shots shouldn't be a problem either, strictly speaking you don't 'have' to have the needle retract at all. I used a few of these way back and I never really felt like it was easy to accidentally set the spring off.
Part of the problem is the video only shows them having the needle retract while still in the body, you don't have to do that at all
Jktm I'm surprised that it hurts you when they take an IV out, I've never found hospital IV's or shots I've done myself to ever hurt when taking 'out'. For me the most painful aspect of a shot is large volumes (anything above .5ml) given SC, hurts like hell most of the time. I find IV to be the least painful of all because if you hit right it's not adding a volume of pressure under your skin.