>I find it kind of strange to spend that time and money on doing something that has little to no productive value.

That's entirely the point. Lawns originated in the middle ages as a status symbol. They demonstrated a) that you could afford to waste a perfectly useful piece of arable land and b) you could afford to pay a team of men to neatly scythe and shear it. It's hard to tell how much land an aristocrat actually owns, but the size of their lawn acted as a reasonable proxy.

The invention of the mechanical lawnmower helped to democratize the lawn, establishing it as a symbol of middle-class suburbia. A small lawn in front of a suburban house didn't demonstrate that you were gratuitously wealthy, but did demonstrate that a) you could afford a larger plot of land than strictly necessary to accommodate your house and b) you had leisure time to spare.

Well not really My grandparents lived in a council house (with outside loo) in Birmingham (uk) and if you don't keep your garden looking nice the corporation would evict you.

I suppose it varies regionally. To me, merely owning a lawn is something reserved for the upper crust, let alone having the time to maintain one. The middle class lives in small apartments and rents houses (with roommates or extended family).

Everyone in the Bay Area was was forced to step down a class so that the tech boom and neighborhood character could coexist. Owning a (modest) suburban home for your nuclear family is baseline middle class everywhere else. Renting (and especially renting with roommates) is for students and the poor.

That's mostly a symptom of a shrinking middle class, in my mind.