You seem to be mixing the concepts of URI rule processing and query string handling.
URI rules are used to parameterize the URI. For example, 'GET /address/{zip}' is looking to parameterize a value that is coming in the URI such as 'GET /address/123'.
Your example endpoint is sending a query string. For example, http://localhost:8081/address/?zip=123 In other words, your URI is GET /address not GET/address/{zip} in the preceding example.
OOTB, DevTest parses query string parameters into request arguments. This is why you see the property request_zip = 123 in your picture.
The URI rule /address/{zip} is looking for a URI containing "address/123" so that the value '123' is parameterized.
If for some reason you wanted a URI rule (/address/{zip}) to parse a zip and a query string, you would send:
'GET /address/75166?zip=123' Personally, I would use a URI property name other than 'zip' if a query string value could also have the same name.