I don’t know about it in in Buddhism, but for Christians, one of the basic commandments is “thou shall not kill”, but they seem to ignore it fairly regularly. If you want to know about extreme nonharmful peoples, you could look up the Jain monks. Some of them wear masks to avoid killing bugs with their breath, and take care how they walk so they don’t kill grass. They have a similar approach as Buddhism, except far more extreme, in believing that rebirth is imperfection and suffering, and that the final goal is escaping the cycle of rebirth (liberation, moksha, or nirvana.)
In contrast, rebirth is required in Christianity (according to Jesus’ teaching about it to Nicodemus) and though various things are forbidden as sins, everyone is expected to be imperfect and sinful, so if there is a Christian cult that says “please don’t walk on the grass” then there should be some way to achieve forgiveness for stepping on the grass or bugs or whatever. Mainstream Buddhism was this similar easy-going attitude — the goal may be nirvana, but unlike for the Jain monks, it’s not something expected to be achieved by any given individual. So, basically, mainstream religions aren’t extremist, they don’t do extreme things like forbid everyone to step on bugs. I hope those thoughts help.