Drones are not exactly quiet. The vast majority of cats travel very quietly indeed, and generally do not arouse suspicions wherever they go.
Unless they go in a dog’s yard, sometimes.
The only advantage I see to the cat vs. just driving down the street with the same stuff in your car, is that cats routinely go in back yards and so on without anyone’s notice or complaint. But then, what’s the point of being able to catalog a network because your cat can go somewhere you can’t. How will you use that information in any useful way?