Watch this, it’s all quite Fup

Here you can take a deeper dive into details.

Robertson’s efficient manufacturing technique using cold forming for the screw’s head is what made the idea a commercial success, so it looks like Canadian popularized it, even though it was patented by US earlier but not commercially manufactured.

Image source

I’ll add few more here, in case someone wants to know how some of the screw heads mentioned look like.

Good comment to add some more info here. I wasn’t trying to claim superiority of this screw. As an afterthought I figured that adding that additional cut for flathead screwdriver compatibility, could have been helpful with stripped heads recovery. I’m gonna try to buy some of those canadians screws, looks hard to strip.

Devs should provide some info for donating directly in-app (something like this example below, and definitely give a few choices not paypal only. For me, whenever there is available buymeacoffee (in app I frequently use), I make donation with cc.