This is something the article doesn't mention, but we learnt in our early teens helping to fit wheel nuts, and of course they look better dome side up.

Loading is probably where I would start - we can take the 40ft container maximum load(capacity+container) as 29tons, divide by 8 to give 7250 lbs.

I discovered tires have 2 load ratings, 150/149 would mean 7400lbs in single configuration, 7150lbs in double. So there is a little inefficiency in concatenated configuration.

Google easily finds me 40' 4-axle trailer. Same company provides similarly 2-axles with the wheels doubled up.

https://www.cheetahchassis.com/containerchassis/40-lightweig...

"if you want to maximize your capacity for certain applications" ..the 'why' still is not answered.

Best I can come up with is the 4-axle config creates tire scuffing (so cost), more axles = more friction = fuel cost. And worse handling.

(But cost is a good thing, if you're marking it up & charging the customer right? - not sarcasm, it's from the link)