Or you can read it another way - they DO compete - in as much as they all drop their prices to match whoever is prepared to take the least profit.
Which looks the same (externally) as all not competing and agreeing to a fixed price - so there's no way (unless someone who is actually involved in setting prices at a camera retailer decides to comment) to know which is the case.
I can talk about a similar market which I used to work in, computer retail, specifically Apple computers.
Back in the 1980s, (the limited number of) Apple resellers made healthy gross margins in the order of 30%.
By the early 90s, when I entered the industry at a newer mail order Apple reseller, we were looking for 12 to 15%, which drifted downward over the course of the next few years.
Skip forward to the turn of the millennium when I had moved to a distributor (I knew what the wholesale prices were and Apple certainly did not do volume discounts) many of the retail competition were clearly working on margins as low as 2.5%. On a £1000 iMac sale they were making £25, hoping to make things up in volume and accessories sales accompanying à new computer (which tended to be more profitable).
To anyone outside, the £25 difference between them and another company selling the computer for £1025 might appear nearly trivial, but that was a doubling of the profit to be made. Equally, another retailer offering the iMac for £995 was losing 20% of their gross margin versus the first,*
Flipping through the ads in MacUser, you might imagine it was almost a cartel conspiring to keep prices high, when in fact it was quite the opposite.
* none of this probably stopped customers asking for ’the
best price’ expecting to be able to get £100 or more off the sticker price, which would have been a loss for the retailer.