Some bugs evade bats. Bats don’t eat all types of bugs. So, yes, they choose what bugs to eat and which not to eat.
Bats and bugs are part of a symbiotic natural system that balances. Bug zappers are not. Zappers kill all bugs they touch and are designed to be irresistible to bugs. They have a startlingly high kill rate. And bugs do play a very important role in ecosystems. It’s not advantageous to kill every insect.
It was proposed that a bug zapper would be more effective.
You countered that it indiscriminately killed, specifically mentioning (among other points) that it will kill whether or not the bug eats books.
This certainly seems to imply that you hold the opinion that bats do not indiscriminately kill and will further more take into consideration whether or not their prospective lunch eats books.