A couple basic questions

1. DO NOT ASSUME.No they are different.
2. Never bench, nothing like a car .
3. No, lack of following distance, driving to fast conditions.
4. Yes and no, HAZMAT has restrictions, also depends on where the delivery is.

Go for a ride in a trucks,

 

First truck I took my test on was a bench seat, so you certainly can't say never. It wasn't adjustable nor did it have any sort of air or spring under it.Also, it had the more traditional clutch layout as opposed to being all the way to one side. It was IIRC made in the 70s it had spring suspension and a 5+2. Such things are on the road still. I appreciate my modern air suspension bucket seats I have in my truck now.

As to the op, I95 (dc metro, Baltimore, etc) has hazmat restrictions on the tunnel in Baltimore IIRC, I think I695 is the allowed route, but I don't carry hazmat so I am not 100%

 

Not really a truck, more like a uhaul

 

Looks like you've done your homework and have a good grasp on trucks

 

Petroleum products are distributed by barge and pipeline.
Every so often there is a distribution point on the pipeline that serves a given area.

I worked for a carrier hauling gas off the Buckeye Pipe at Macungie, Pa.
When they had a problem I would pick up tomorrow's papers and drive to Scranton for the night and meet our trucks at the next point north in Pittston, Pa. and hand out the papers.
The distances are short so the truck makes multiple deliveries around the area.

Chemicals do go longer but most are more regional.
You have storage facilities in large cities, as well as, individual plants here and there.
Plastic resins [dry bulk] is more regional than long haul.

 

There is a company that sends tankers filled with Disal SG from Ontario down to Green Cove Springs, FL, so people do truck various chemicals on long hauls.

 

Just because it's done that way where you are at doesn't mean the whole country does it that way. Every gallon of gasoline that gets shipped through a pipeline gets loaded onto a truck to go to a station. UNLESS of course you have a pipeline that goes right to the station. There's more trucks hauling gasoline than there are pipelines. There's more gallons of gasoline being moved by trucks on any given day than pipelines. So I'm sorry your statement is just ludicrous.