The thing these examples have in common is that they don't give you any inherent advantage that invalidates the purpose of the test. (Assuming it's not a handwriting test, or an 'ignoring distractions' test.)
I would group all of these along with the examples I gave: corrective glasses, and wheelchairs. They should be available to all students, without diagnosis or discrimination.
If you think limited time on tests doesn't serve a useful purpose, then why give 'extra' time to only some students, and not to all students?