Some random questions about low BR tanks missing HE

I got curious recently and i look at Wikipedia and saw that a lot of low BR cannons have HE ammuntion IRL (and enlisted) but not in WT

The german 37mm tank cannons have HE. Along with the czech 37mm.

Russian 45mm O-240 HE

Japanese 37mm had a HE, and that is actually in the game but it’s only found of like 5.7 BR jap tanks.

Heck, the french SA 18 L21 has a AP and a HE too, but why aren’t they added at all?

For the SA 18, i can get why the AP isn’t added, low pen. But why are all low BR low caliber tank cannons missing thier HE shells?

Is it balancing thing for low BR open tops?

I can get missing HE shells for vehicles who were around before the HE was introduced. Like the M63 for the American 37mm, or the british 40mm Shell mk.ll

It’s weird to me