Hello Deeksha, I may add to what has been said by the learned member, I couldn't guess what prompted you to think along these lines. Human beings are social animals, and animals have their lives cut out. In the evolution of humankind, everyone has reached a stage where "man does not live by bread alone." Because man does not live by eating alone, he also has to make his life "meaningful." If eating alone were the only 'life,' man would have stopped growing grains and no longer worked. But after thousands of years of human life, we needed many things other than bread. We work, earn, eat, clothe ourselves, but also have to do many other things. We are not machines; a machine can be idle once switched off and remain as a machine. But man? Imagine trying to be idle, doing nothing. Don't speak, don't hear, laugh, weep, quarrel, fight, move around, and so on. Try for a day; you can't. Even a madman can't remain frozen. That's what social life means. We have certain duties to perform outside office work/duty. We don't feel alright, unwell, and attend functions, go shopping, worship, travel. Family and domestic obligations must be fulfilled at any cost. Even a sage/hermit/recluse/eremite who renounced worldly affairs has some other duties to perform. And for that, they require off-duty, and thus leave is availed, no matter what you call it. Why, for instance, do many units still not have a kind called Casual Leave? But still, they would have EL or PL, Sick leave, Maternity leave, etc. Yes, you are right; persons like peasants/farmers, freelancers will have no leave of these kinds, but they may take 'leave of absence' from their routine. No approval from anybody would be required. They are not employees but professionals. So ultimately, you have to shun the tag of 'employee' and become a professional/self-employed to eliminate 'kinds of leave.' Will you?
But every citizen has to abide by the law of the land and governance enabled/done by various pertinent regulations and stipulations to ensure minimum requirements. One among them is the Leave policy. Policies may differ, but leave stays put in one name or another.