You're comparing two totally different things. Planes flying at 40,000 feet are flying in air temperatures around -70F. The jet engine exhaust is between 1,200-1,400F. That's quite a big difference in temperature. It takes a long time for the jet exhaust to reach the ambient air temperature at 40,000 feet, hence why it lingers and takes awhile to dissipate.
Car exhaust is about 400F...and obviously our ambient air temperature at ground level is nowhere near -70F. Have you ever seen car exhaust on a hot day? Not likely.
As for 2 planes flying at "roughly" same altitude and one emitting contrail and one not...again, humidity can be completely different even if flying at 1,000 feet difference. There are so many variables that would effect this to make the difference. Show me a video or some irrefutable evidence of this exact scenario - 2 planes, same altitude, same airplane make/model, same flying speed, in same geographic area, one with contrail, one without, and I'll consider it.
I won't even go into the jet fuel issues with your thoughts on "chemtrails". Do you really think they are manipulating jet fuel by putting chemicals in it to create these "chemtrails"? Do you even have a slight understanding how difficult it would be to do this? A combustion engine would completely change the added chemicals before going out the exhaust. Jef fuel burns at 3,000F.
The question above asked, why on some days there are lines everywhere and on some nothing? Well....I answered that. Educate yourself with a little basic science in this short video. It addresses your question about "lingering" at the end of the video. Have you ever watched clouds form over a mountain range throughout the day? Same principle.
It's called humidity. Same as the exhaust coming out of your car. Some days you see it coming out of your car, because of the higher moisture levels. Some days you don't see it (drier days). Same goes for warm/moist airplane exhaust coming from the engines. As this warm/moist air cools, you no longer see it. That's why it vanishes. It's moisture. Humidity levels change every single day. Same goes for your warm breath on a cold & humid morning. It disappears as it cools and reaches the same temperature as the air temperature. Basic science.
We've all been told we're "watching a movie" playout. Did we really see all these people dying in chem fires and in the Afghan withdrawal? Ever watch "Wag The Dog? Obviously inflation is real, and I think that is needed to help wake the sleepy people up and realize the financial system is completely f'd up. I think the hard times now (and even worse to come) are needed to make people start looking deeper and realizing what is going on around them.
You need to follow Derek more - he explains all of this and has posted many videos with details explaining these exact things. Most of what you are seeing are “optics” and is all part of the great awakening process, with military being in complete control.
Found this website searching on Brave. Has some more detail on the photo. That definitely is not a small bathtub. Looks more like a plastic storage tote, suitcase, or even an electric turkey roaster.
Were all the jets the same make/model that took off out of SLC? There are so many variables that contribute to contrails. Do some research. Would love to see your evidence that shows that exact same airplanes (make/model), same time, same altitude, same weather conditions, same engines, end up producing two different outcomes (no trails vs. trails).