According to the service manual there is no such thing as a 45,000 mile service. Changing the brake fluid is not mentioned anywhere. The transmission oil is changed at 50,000 miles under severe service such as trailer towing otherwise use the oil life monitor. Fuel filter is changed on inspection. The injectors don't need cleaning if you use "Top Tier: gasoline. Sounds to me like they're trying to service you like the bull services the cow.
I have about fifty years of hands-on experience in the maintenance of everything from sewage pumping trucks to guided missiles. History shows that the opening up of a working sealed system in the name of preventive maintenance is about as likely to do harm as good. In order to verify that all is well you run the risk of introducing foreign mater, getting the thing reassembled incorrectly, and/or, not getting it sealed back up again. Over the years, I have seen that the more inspections you do and the more maintenance on condition you do, the better off your operation will be. The only rationale behind blind, on-schedule disassembly is to establish a pre-failute scheduling scheme. Cadillac has done this and published the results in the form of a manintenace schedule in the service manuals. The dealers don't like the idea of extended maintenace scheduling because it cuts into their bottom line. The result is these cockamamey maintenance items they dream up and spew to the customers.