it's not the same. even if you are similarly "conditioning growth" in both cases, you don't care the same about both things. with lawn, I'd say most people are mowing to "prevent something ugly" more than to "make something beautiful". with the bonsai you are actually trying to make something beautiful. in a way, you are not just "conditioning", you are "designing". it's less about something practical and more about personal preference, more opinionated. and it doesn't happen only with plants. some people like myself are a bit reluctant to share certain things with others, wary that it might change the way they see the world. I wouldn't say growing bonsai is cruel, but I kinda feel it cruel, and I'd definitely avoid doing it.