I agree with your point "I tend to rate basically everyone in service interactions 5 stars because the fact they even turn up to their minimum wage job is a colossal privilege for me to enjoy."

But one thing I like about rating things is that it gives you a way to flag things that go badly. That's what sucked so much about taxis - you'd be ripped off, forced to pay cash, order a car only to wait (and then it not arrive), or wait out for 30 minutes to flag one down. Drivers would be rude, they'd talk on their phones, they'd drive dangerously. And you'd have to grin and bear it (I've experienced all of the above).