It's all green, but there's an industry and several efforts to replace natural grass with synthetic materials, plastics like polypropilene (PP) or Polyethylene (PE). From the origins the artificial turf principally employed polypropilene, the widely used plastic with a considerable strength for fatigue and with good resistance. It seemed right for the purpose although after years this solution had gained bad reputation with problems like more tendency to injuries due to the hardness of the turf or by abrasion with the plastic. The ball could also experience greater unpredictability, like conserving a linear direction or in bounces as the surface loses fibers with time after the degradation caused by the use and the rather extreme environment. A solution was to migrate toward Polyethylene with a substrate of silicon sand and rubber.
The synthetic turf is also prone to experience problems in seams, where the two pieces join. Also UV radiation has considerable effects on these plastics. It's also expected that the plastic pieces suffer expansion and contraction due to temperature changes. And not the first time that some manufacturers include heavy metals like lead in the production process.
Natural grass could grow everywhere (well, in space too) and without time limitations with accessible factors (water, seeds, fertile ground and equipment for maintenance), while synthetic materials normally have a warranty period and after it, it would be necessary to replace it or handle the problems by resignation. This is a good opportunity for a business, when the usage times for the field are lower and after some years there's another bill to appear, and in a constant manner. Growing money like the natural grass. Artificial grass is usually presented with less cost for maintenance but let's remind how these values aren't linear by nature.
Synthetic plastics express, obviously, better resistance than natural grass allowing more hours of intensive use without considerably damaging the field. This resistance is the cause of the environmental contamination caused by plastics, with even their location in the ocean during decades. In the other side is natural grass, a more delicate luxury that has a natural odor and touch. It slides wonderfully as it has an intrinsic component of humidity and breakage.