Why most languages use special names for the numbers 11 to 19?

Question

For example, some languages follow the same rule regardless if its in 10s or 20s:

Japanese | Chinese |
Juu-ni | Shi er | twelve
Ni-juu-ni | Er shi er | twenty two

But other languages such as:

English | French | Romanian | Icelandic | German | Philipino |

Twelve | douze | doisprezece (two towards ten wtf) | tólf | zwölf | labindalawa
Twenty two | vingt-deux | Douăzeci și doi (two tens and two) | tuttugu og tveir | zweiundzwanzig (two and twenty) | dalawampu’t dalawa

Initially I thought it was an european thing but not even koreans do it like japanese or chinese people, so why is that?

In: 38

Answer 1

Hold on, 11 in Japanese doesn’t have a special name. It’s just 10-1 (ten-one).
10,000 has a special name, though: 万 (‘mahn’).