RabbitMQ
No evidence is not evidence of nothing.
Marshall talks to RabbitMQ through the management HTTP API. Listing queues, their depth, consumers and bindings is a plain read and costs nothing.
Reading has a cost
RabbitMQ has no way to look at a message without consuming it. Even when the message goes straight back to the queue, its redelivered flag becomes true for good, and some consumers treat redelivered messages differently.
So on RabbitMQ, Marshall never reads on his own. The first time you open a queue on a broker, he explains the cost (Reading this queue will mark it) and waits. Read it anyway goes ahead; he asks once per open broker.
Nothing is lost: every message goes straight back, and the queue depth does not change.
Bindings
Each queue shows what is bound to it and with which routing key. A queue bound to nothing says so: only a direct publish by name reaches it.
Counting
The first screen keeps two counters, messages read and messages disturbed, because a RabbitMQ read is not a Kafka read.