I'm proud to say I know what 3 out of 4 of those do... The Holes in the shoes are to allow humid air to escape so your feet don't stink.

The Fat section of the power cord it to disrupt stray electrical signals coming from the wire so they don't interfere with other electronics.

The Rivet in the pocket of the jeans is to reinforce the pocket so it doesn't rip back when miners would put the nuggets they found in the pocket originally made for watches.

I honestly have no idea what the fourth one does.