Architect here.
That amount of green is mostly shown in early renderings made by unrealist young architects or by CG artists. A rendering is just an ad, a way of selling the project and having areas of greenery is highly regarded as positive by the market. After the project is "won" that "details" are scaled down to meet reality and budgets, this time by more experienced architects pressed by investors and a ton of technical advisors.
Correction: The article's image that is wrongly attributed to "Villa Bio by Enric Ruiz-Geli" should be attributed instead to "Outrial house by KWK Promes".
http://www.archilovers.com/projects/42124/outrial-house.html