Why does go.exists() require a different url from msg.post()?

Questions
6

I had an idea to try to confirm that the collection:/id pattern in fact works for sending messages into the loaded collection, seems so:

	case.GameTestCase_can_send_message_into_a_collection_under_test = function(self)
		-- Given
		local proxy = "/tests#testproxy1"
		self.util.loadCollection(proxy)
		self.gassert.receivedMessage(hash("proxy_loaded"))
		self.util.initCollection(proxy)

		-- When
		self.util.sendMessage("undertest:/xunit_is_cool", "create_bullet", { position = vmath.vector3(5, 5, 0) })
		
		-- Then
		self.gassert.gameObjectExists(proxy .. "/bullets/instance0") -- works
		-- self.gassert.gameObjectExists("undertest:" .. "/bullets/instance0") -- times out
	end

DEBUG:SCRIPT: Created bullet: [/instance0]
DEBUG:SCRIPT: Suite: Game Tests Suite
DEBUG:SCRIPT:   GameTestCaseTests.GameTestCase_can_send_message_into_a_collection_under_test: OK (0.081s; 6 frames)
DEBUG:SCRIPT: 1 run, 0 failed

Note: self.util.sendMessage(...) is just a wrapper for msg.post(...) to happen eventually after the other steps completed.