[fjtorres]

Sooner or later you need to reconnect to get new books.
Otherwise you're giving Amazon money for nothing.

Theoretically, you could sign up, download ten books, and then cancel and never ever connect again just to spite the authors but, seriously, what's the point of that?
(And Amazon will notice.)
At most you'd be stiffing them $10-20.
Anybody who would bother with that is more likely to go for bigger targets and there really is no shortage of books out there for the unethical; entire libraries by the thousand so why bother with a handful of titles?

The kind of person that signs up for KU is typically a heavy reader who intends to get their money's worth. Which means refilling the reader regularly.

And, remember, the reason authors put their titles in KU is for a visibility boost that pays. Visibility comes first.

To put it another way: KU is paying out over $100M a year. Pilferage on the order of $20 isn't going to break the system.
It's no biggie.