I was going to explain stuff, but given I’m verbose as fuck, it’s simply easier to link Wikipedia. A few highlights:

sees 10 distinct colors looking at a rainbow, whereas the rest of us see only five.

The number of distinct colours you see in the rainbow isn’t just dependent on your colour vision. I have an in-depth explanation here (up to the traffic light), but to keep it short: what you consider “distinct colours” or “hues of the same colour” is largely culture-dependent.

Plus it depends on the rainbow itself; example here

You’re likely to distinguish way more colours for the inner rainbow than the outer one. (For me it’s six vs. three)

“A true tetrachromat has another type of cone in between the red and green — somewhere in the orange range — and its 100 shades theoretically would allow her to see 100 million different colors.”

Emphasis mine. While tetrachromats are expected to have a fourth type of cone between the red and green, people with cones elsewhere wouldn’t magically become “false” tetrachromats.

Unfortunately, in this day and age it would likely be very frustrating, especially since most tetrachromats are likely unaware of their unique abilities.

This was written in 2001. Say hello to 2025. LEDs make this trivial - because they allow you to reliably produce light in narrow wavelengths. For example, a mix of 620nm (red) and 530nm (green) lights would be completely different from 570nm (yellow) light, even if for trichromats they’re the same type of yellow.

To a tetrachromat, television and photography would fail to reproduce colours correctly.

I think a good equivalent would be a TV without one of the colour channels… say, if the TV is missing the green channel it shows purple, green and grey all the same. For tetrachromats all TVs would be like this, since they’d be missing the fourth colour channel.

Further genetic info: humans encode colour vision into the chromosomes 7 (blue opsin) and X (red and green opsins). At least in theory you could have a mutation in one of those three genes, that makes the associated cone cells absorb light in a different wavelength; and, if the person has both the mutant and ancestral alleles of the gene, at the same time, they would be tetrachromat.

In practice this means that tetrachromacy among men is possible, but you’re far more likely to find it among women.