>>1073140They were associated with royal estates in ye olden tymes, basically a sign that you not only have more land than you know what to do with, but you also have so much money that you amuse yourself paying peasants to cut plant vegetation in arbitrary lengths and patterns for reasons completely unrelated to farming.
When industrialization happened, the new middle class wanted to be like royalty, so they put lawns on their little squares of land to show off that they don't need the soil to grow food.