Having a single glyph doesn’t make things any more precise or scientific than two glyphs (or three, or four, or a word, or whatever). If an individual glyph is hard to type, it’s entirely sensible to use more, easier-to-type glyphs.
If glyphs were really the way to go, we would switch, when possible, to single-glyph symbols instead of method names. For instance, a.map(f) might become a 變 f.
I don’t have any more trouble distinguishing => from <= than I do distinguishing the words “ob” and “do”. If you have trouble distinguishing and/or recognizing => as opposed to <=, use a font with ligatures. That’s what ligatures are for! Traditionally, it was for getting pretty-looking ff and fi and such, but it’s a general-purpose tool that solves the problem you’ve identified, and people have used it to solve this exact problem.