It’s just a poorly defined metric. “Product complexity” is computed by looking at the countries which export the product. A product is “more complex” if its exporters make a lot of different products, and those things are commonly exported by other countries too.
So photographic equipment is only made in a small number of countries (germany, japan) which are very integrated in the world economy. Processors probably fare worse because Taiwan makes them and is “insufficiently” complex.
Eyeballing the rankings the methodology is probably biased towards manufacturing materials supply chain complexity rather than "knowledge economy" complexity.
Nevertheless its probably directionally correct at more aggregate levels.
Making a CPU requires exactly "photographic plates and film, exposed and developed, other than motion-picture film", i.e lithography and more and more extreme wavelengths.