What's the most petty/pointless/pedantic hill you're willing to die on?
For me, it may be that the toilet paper roll needs to have the open end away from the wall. I don't want to reach under the roll to take a piece! That's ludicrous!
That or my recent addiction to correcting people when they use "less" when they should use "fewer"
Actually you can count to 12 quite neatly on one hand. Simply take your thumb and place it on the bottom segment of your little finger. Excluding your thumb, you have 12 segments on your fingers.
As you count, move your thumb up one segment, switching to the next finger when you reach the top. This way you can count to 12 on one hand.
You do realize you can still count up to 5 with your fingers even if we used a different numeral system? So you would signal in the exact same way that you do now. Or you know, just shout or something? How often do you need to signal a small number from a distance?
12 has more prime factors than 10. 12 has 2, 3, 4 and 6. 10 only has 2 and 5. This also means that thirds and quarters are much easier to do everyday maths on and those fractions are much more common than fifths.
For example, in base 10, a third is 0.33333..., going infinitely. But in base 12, a third is just 0.4. The times table for 2, 3, 4 and 6 is also much easier.
Tau makes much more sense than pi because it is based on the radius of the circle rather than the diameter. The radius is the more fundamental property of the circle. You'll actually see 2pi appear in many formulas. See also https://tauday.com/tau-manifesto
The primary reasoning I've heard is that it's easier to do arithmetic with numbers that are factors of your numeral base and 12 has more factors than 10 (1, 2, 3, 4, 6, 12 vs. 1, 2, 5, 10)
Base 12 seems a little impractical to me since humans have 10 fingers, which makes base 10 easier to teach to children, but it's a matter of opinion i guess
τ is equal to 2π, which allows the formula for the circumference of a circle to be written more concisely (τr vs. 2πr or πd) but complicates most other places where π is used, like in the area of a circle (τr^2/2 vs. πr^2)
My response to the 10 fingers thing is that it's easier to do certain calculations in your head. A lot of those calculations are larger than 10, anyway, so your fingers don't help.
A third of 24 is 8. A third of 60 is 20. It becomes second nature after a while.
One place I used this a lot was 40k. In between rolls, I grouped my dice into sets of 4. When the next roll called for 12 dice, I quickly pick up 3 sets. If it's 10, pick up two sets plus two dice from a third set. Made it really quick to count. At least for the base rolls, a lot of the stats in 40k tend to work in multiples of 4, so this worked out.
The nice thing about a foot is that it divides into 12 inches, which gives you many options for measuring portions of a foot compared to metric units. But the problem is not with the metric system. It is with our base 10 numerals.
It's actually not that hard to count to 12 on your fingers. You can even do it on one hand by pointing your thumb at the sections (phalanges) of your fingers. If you bring your other hand into it, you can even reach 144!
Regarding the τ = 2π thing, I brought this up with my mathematician/classical Greek enthusiast brother. He said "Tau? Why tau? I would've gone with Ϡ (sampi). It's not used for much anymore. Would be great to bring it back…"