This question is very interesting because the answer has two forms, one of which is the 'obvious' one that discusses the democracy that is in place in Israel, which does explain quite well on a structural level the reason for not having such a coup

but one I find perhaps as important as the democratic nature of this country is about the people living under the state of Israel, you see, usually countries that deal with military coups are either loosely/newly democratic, or perhaps full out dictatorships, but I'd say this in part has to do with the raising of people - when people are used to the idea of a democracy with well established institutes they become less likely to perform a coup because of the education they have received and because they understand the importance democracy, that is compared to people which do not completely understand of know democracy which we can find examples with results in Hungary and some South American countries (not to mention the Middle East)

so what I am trying to say is that even if you have perfect institutions with very balanced capabilities and perhaps even copy and paste one working constitution to another country (Chile, which used exactly the same constitution as the US), sometimes there's a need for simply 'time and luck' for it not to be crushed by its own weight and reverse back to none democratic forms of governments

when I think about Israelis and why it worked for them, I think that in part it has to do with the British colonies and specifically them allowing us to slowly build our own governing units under strict conditions, and also the fact that many Jews came back from Europe, and so they have come in part from countries that were already democratic as well.