One might argue that almost anything audio related has audible variations sample to sample within the exact same model. I'm not just thinking cartridges but things like headphones, speakers or anything else electro-mechanical in nature. About the only thing I can think of in audio that is guaranteed to be the same from sample to sample is software!
Mind you, I have never heard any identifiable differences between components that were not electro-mechanical and had similar burn-in times. I have heard differences between identical headphones despite equal burn-in times though as most people would appreciate, the frequency response and driver outputs are usually going to vary very slightly from one sample to another - even at the high end.
As for cartridges, in the main I tend to agree that measurement / build differences between individual cartridge samples tend to be dissipated amongst other more pronounced variables. That said, left/right channel balance and possible associated azimuth adjustment issues - due to an imperfectly mounted cantilever (but more likely an imperfectly mounted stylus on the cantilever or combination of both) are variables between samples that I am not prepared to tolerate. Having heard what a "perfectly" mounted stylus / cantilever can achieve versus one where you might have to minutely re-align the cartridge body to account for imperfect alignment, you are not getting your full money's worth unless you try to get a "perfect" one. Less than perfect and channel balance, cross talk, imaging are going to be slightly compromised compared to that of an "ideal" sample.
This is why it pays to get a cartridge from a company that fully hand builds using skilled artisans and has very strict quality control. Sadly, although I am a fan of the Ortofon sound, I would actually nominate them as a company where the quality control (specifically as in sample to sample) could be better than it is, though I am only speaking of up to the upper midrange - say Cadenza or lower. I have never looked at their very high end models.