Perfectly green, monoculture (one species of grass) lawns are estimated to be the 4th largest crop in the US (similar in Australia). As far as a 'crop' goes, they give back a very poor yield: They require huge time, water, chemical, and energy inputs...and you can't even eat them. The bugs can't even eat them.
THIS IS A PROBLEM in our current polluted and life-endangered situation
....But it's an easy problem to solve!
WHAT ARE THE ALTERNATIVES?
-Flowers -Veggie gardens -Herbs -Just leave it alone and see what happens -Native trees and shrubs
If you aren't into growing food, no worries. Flowers are a beautiful alternative and the birds, bees, and bugs will love you for it. Likewise when planting some native trees, shrubs, and ground-covers. Otherwise, you could just leave it alone and see what treasures it presents through the grasses' natural life-cycle. At the very least we need to drop the chemical additions to our natural environments. And encourage our friends and family to do the same.
THE NEGATIVE IMPACT OF LAWNS
Although they technically function as 'green space' (which has been recorded as having a multitude of health benefits) in the final tally lawns damage the environment more than they benefit it. The fossil fuels required to mow a lawn, the pesticides and fertilisers required to keep them green and weed and bug free (read; life-free), ultimately make them very damaging.
Lawns are a cultural relic of ye olde England. They were seen as a status symbol. Only the rich could afford the labourers and grazing animals required to maintain such a space. In our current climate crisis, we need to say goodbye to this very odd cultural habit.
BUT WHERE WILL THE KIDS PLAY?
If you keep lawn for your kids to play on, I promise you they will play and explore with far more joy and learning in a diverse garden space than they can get on a lawn.
If you keep a lawn because it is in keeping with what the rest of your street looks like, and your neighbours might get their knickers in a twist, I'd invite you to be the pioneeron your street of an abundant, radical front or back garden. They'll soon see how amazing it is and follow suit.