Mandatory service doesn't mean they don't get cushy jobs (if they want them) though.
Yair Netanyahu was never going anywhere near the front lines (he was in the Spokesperson's Unit), and nor do many other children-of (not only politicians of course, but they do have a lot of influence), they get jobs at headquarters or some other nice safe place, the military bands/entertainment units are notoriously where many a nepo-baby has got their start..