There is a reason why diesel is more expensive than gasoline. Taxes. Several years ago, most legislatures discovered that most consumers of diesel were out of state truckers just passing through. These truckers could be taxed without worrying about taxpayer retribution at the polls. Consequently, diesel is taxed at a much higher rate than gasoline.
You might have noticed that there usually two different prices for diesel. The regular price and the ‘off road’ tax. The taxes on ‘off-road’ diesel is much less to placate the farmers. Off-road diesel has a different color. Don’t get caught with off-road diesel in your diesel powered vehicle unless it is a tractor and you’re hauling hay. The penalties are huge.
BTW, I bought lots of ‘off-road’ diesel to use in my four wheelers. IIRC, it was a distinctive red color. You can drive a farm tractor on the highway when moving from one field to another but the principal use must be off-road.
Same story when it comes to a pleasure craft boat or a commercial fishing vessel.
The lobster boat burning commercial diesel puts out a different color exhaust. The Coast Guard will give you huge ticket if you get caught with it in your sailboat or weekend fishing boat/yacht.
The Federal excise tax on Diesel is 6 cents per gallon more than for gasoline (24.4 vs. 18.4), but here in Texas, the state rate is the same for both fuels: 20 cents per gallon.
In my former home state of California, the rates are higher on gasoline than diesel, but both are pretty high: 51.1 cents per gallon for gasoline, and 38.9 for diesel.
Other states may well reverse those rates as you suggest, but it’s not uniform at the state level.
And I always called dyed diesel “marine diesel”, since the only place I ever saw it sold was at a dock. Interesting to learn that it’s available for off-road land-based uses as well.