Because almost zero percent of cryptocurrency users blindly paste addresses into clients without at least double-checking it was actually the address they wanted to paste. Most of them are conditioned not to trust anything, and double-verify. If you're sending a large amount, you first send a small amount, verify it arrived to the correct address and then send the proper amount.
Verifying the "string of garbage" (which is actually a hash) is simply a matter of checking the first and last four characters, can be done in 10 seconds easily.