To trick people into thinking things cost less than they do so they buy more.

Surcharges exist to allow advertising lower costs and attracting more customers while charging the same or more as competitors.

It may be when the supply chain gets back into shape

It says fuel and inflation surcharge, not supply chain

right but it could also be temporary and Amazon may remove it surcharges when the prices pull back and stabilize.

Not that I agree with Amazon here, but it makes sense not to just increase the fee overall and have it itemized if its anticipated to be temporary (even if thats temporary on the scale of say...1 year)

While inflation may go down, it won't turn negative, so pretending like it could do so is disingenuous

There have been periods of negative inflation [1][2].

Though thats not really the point either. Gas prices DO fluctuate and recently have done so drastically (48% or so YoY). They are a contributor to the overall inflationary trend recently. Though aren't the only cause, or even primary IMHO, they are probably one of the biggest that are noticeable to the common person and one that doesn't scale well.

In 2006 after Katrina i was paying well above $3.00/gallon for gas. That got better over the years and really good in the last year or two. Then its bounced back up.

So again, if Amazon sees this as a temporary trend and cost to their service, it makes sense to itemize it off to allow the option of its removal when it stabilizes and/or reverts, rather than lump it in with their standard bottom line service charge and have to explain not one, but two changes to that down the line (an increase and then decrease).

[1] - https://www.macrotrends.net/2497/historical-inflation-rate-b...

[2] - https://i.redd.it/zij9zxups3t81.jpg