The reason is probably that anything faster than USB 2.0 (480 Mbit/s) and supporting power over 3A/60V will need to have an active marker, and to read that, you'll need something slightly more complex than a connection tester.

That said, these things do seem to exist at this point, as sibling comments have pointed out.

As an aside, it's a real shame devices with USB-C ports don't offer this out of the box. They need to be able to read the marker anyway for regular operation!