Of course, it is perfectly possible NOT to kill plants and still eat them, should you feel any pressing ethical need to.
A great many plant foods we consume consist of the fruit/seeds (seed-bearing part) of plants, and don’t require the killing of the plant to harvest.
Apples, pears, bananas (etc…) tomatoes, pumpkins/squash, nuts, grains, legumes, green beans, berries, the list goes on and on.
In fact, such plants produce very attractive, delicious packages for their seeds SO we (animals) WILL eat them and spread their offspring far and wide.
Even foods like brocoli and brussel sprouts can be harvested without killing the plant, and most home gardeners I know, incl. myself, typically DO…both are the buds which if allowed to, eventually bloom and bear seeds. If you cut a bunch of “buds” off, the plant goes on and the cutting actually stimulates it to produce more “heads”. Like cutting flowers. I regularly allowed my brocolli to live out it’s natural life-span (and eventually go to seed after I’d taken several heads from it)
Same for leaf veggies…spinach, kale, lettuce…I never harvested the whole plant, but planted enough so I could take a few leaves from each and let it keep growing.
The only veggies which REQUIRE the killing of the plant to harvest are tubers (carrots, potaoes, onions, etc…) And in the case of 'taters, one plant produces lots of tubers, so you can dig up some and leave the rest and the plant will do just fine and make more.
Almost all these plants are annuals and die off at the end of the growing season anyway (tomato plants are perinials which will bear year after year if you protect them from freezing, btw)
So if someone wants to take it to that next level and not kill the plants they eat from, it is quite possible (though with the exception of fruit/nuts, you’d likely need to grow your own, since most plants ARE killed in the harvest with modern mass harvesting).
I personally feel no urge to worry about torturing or killing spinach, but just saying.