The problem with photos like the one you posted is there is no altitude reference between the two ‘trails’. Are they co-planar or is there a significant height/distance between? Just sayin’.
My picture is not intended to convince anyone or prove to anyone. Intent was solely to prompt questioning, as you have done. The vid link talks more about your point, as does many others, too numerous to ever dig into all of them.
For effective chemtrails, they are dispersed at mid-level flight levels, like 25,000 feet. The goal is to disperse and the particulates sink to ground level.
Higher flight levels, like 35,000 feet, would not be effective, as they’d compete with higher winds (think jetstream and thereabouts).
So the contrail in that pic is in the vicinity of 35k, and chemtrail in the vicinity of 25k.