There can be a lot of differences in components among cameras with "identical" specs from different manufacturers.
Most components are rated for various tolerances, the most common example that people might be familiar with is resistors. High-end resistors will be rated for a 1% tolerance, low-end ones might be 20% tolerance. Similar specs for capacitors, inductors, and all the other components that go into an electronic device. If there is a lot of variance among individual components device to device, you increase the chances that 5 identical models of the same camera all produce slightly different images.
Similarly, you might find that components from different suppliers respond to temperature extremes in different ways. Stability over a temp range is important, as is overall longevity. I think that several people here would remember the electrolytic capacitor fiasco of about a decade ago that caused lots of motherboards in PCs to suddenly fail.
It's hard to really communicate this in marketing material, you're somewhat limited on a datasheet (trust me, space fills up fast), and it's hard for people to *see* or *test* that. If I tell you my camera is from all components with 1% tolerance, how do you know? Or how do you know that it matters? How do you know that the components actually *have* those values and it's not just the component supplier telling me a lie that gets passed on unchecked?
More conscientious manufacturers in all industries tend to work with their suppliers to ensure the integrity of discrete components. It's also common to do sample tests, pulling random finished goods from inventory before shipping and doing a thorough quality check on those devices to ensure they continue to meet stated specs. A manufacturer that is just going for highest volume/lowest price will commonly not have the ability to do integrity checking. As long as everything is living up to expectations (supplied components maintain their quality, assembly processes are followed, seals and gaskets are sealed and gasketed) then it's not an issue, but when something bad happens in that situation it can affect 100,000 units in the blink of an eye, and you don't hear about it until the failures start showing up in the field.
It's more expensive to pay attention to the details batch by batch, and of course you tend to see this in the MSRP of the product. But you also (hopefully) see it in reduced failures, longer lifespans, more consistency unit to unit.
Even with all this in mind, you may still have situations where failures occur in the field in large numbers due to unforeseen circumstances, but you definitely cut the probability way down with proper attention to QC.
There can also be hesitation to call out the discrete components too directly because you don't want customers getting hung up on the wrong things. The CMOS vs. CCD "battle" is a good example of this, you get people that go on believing that the technology or component brand that was best in class 5 years ago is forever the best option. As a manufacturer you really want customers buying your product (mostly) not the sub-components it's made up of.
Another example would be telling you that my camera is capable of X # of simultaneous streams or Y fps because I'm using a particular microprocessor that is better or faster. But those features are also a function of efficiency of the code and other factors. Another company could slap the same processor in their camera with suboptimal code, but hold it up as being "just as good" as my camera because it has that same quality component.
So, you don't see the discrete components called out as much as the finished product, but you tend to the see the manufacturers confidence in the product made up of these components through things like warranty period, or RMA policy, or higher-level ratings (an IP67 instead of IP66 rating, a temp spec covering a wider range).