[RamblingCTO]

We don't care for how much volume fits onto a spoon, we use it because it's normal cutlery. We have bigger spoons for eating soup (Esslöffel) and tea spoons (for desert or something like that). It's not really for measurement but it's used because everyone has it. I think a tea spoon would most probably have something around 2-3ml and not 7.5. Don't trust everything that's on wikipedia. Here they have different measurements for example: https://de.wikipedia.org/wiki/K%C3%BCchenma%C3%9Fe

So basically TL and EL are not for measurement but used anyway. Things get funny with a "gestrichener" (flat filled spoon) and "gehäufter" (as much as you can fit onto a spoon imho) Löffel.