And 99.99% of the time it's measured with a rubber ruler.
I've often thought the same thing but couldn't come up with as colorful a way to say it.
If the screens on a chronograph are 24" apart, the timing mechanism would have to be accurate to +/-0.000025 seconds to see a 100fps difference at 2900 ft/sec.
Olympic timers aren't that accurate, but we expect a $100 chronograph to do it?
edited to add:
I'm not diss'n anyone's chrono or their use of one. I just don't see how they could be accurate enough to determine spreads to the degree of accuracy they claim. Has anyone put several end-to-end to see how close they are?
I'm wondering if it may be the case of always knowing the time if you have one watch and never knowing it if you have two.