Why don't we call an equilateral triangle an isosceles triangle?

Isosceles and equilateral triangles Worksheets

Focus The University of Tokyo

Why do isosceles triangles have two equal angles? - Quora

Can an equilateral triangle also be isosceles?

Focus The University of Tokyo

Draw an isosceles triangle that is not equilateral, and show

Polymathematics: Morley's Theorem

The University of Tokyo on LinkedIn: Why don't we call an equilateral triangle an isosceles triangle?

Proofs concerning equilateral triangles (video)

I don't understand the logic here : r/askmath