The entire point of making this form of ID is to make it a friendly user experience, to create an ID that can easily be communicated by a person over the phone

The entire point of making this form of ID is to make it a friendly user experience, to create an ID that can easily be communicated by a person over the phone to another phone, to make an ID that is easy to click, double-click, tap (with fingers on a touch surface), double-tap, hold-and-select and tap to 'copy', and so on. The _ and - symbols make this difficult in the edge cases of all of the above. Do you call it dash, or underscore? Line? Hyphen? Binder-strich? &etc. I would have gone with adding the @ and ~ symbols, those are at least parsable in human form as well .. ".. email symbol and squiggly thing .. "