system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why are tennis courts different materials?

Pro basketball always on wood. Pro football (US) mostly on grass. Why do tennis surfaces vary so much?

Or is it just green clay sometimes?
gpt
It comes down to what is easily available and, more importantly, what is easier and cheaper to maintain.

Historically, all courts were grass. That was the natural surface available. However, in order to have a playable grass surface, it needs a *lot* of maintenance. You need the right kind of grass (and soil), and it constantly has to be mowed and kept up to standard in order to have consistency. The grass will deteriorate as the match our tournament goes on, and takes longer to dry out after rain.

Clay courts were a great alternative, especially in environments which were less favourable to maintaining grass courts (Europe, South America). With advances in materials and manufacturing, hard courts became more feasible and are commonly used for purpose-made arenas. Grass courts are maintained more out of tradition.

In contrast, football is always on grass because it is normally the most versatile surface for the sport. The quality and condition of the grass is not important, as the majority of the sport involves running and the interaction of the ball with the grass is not as important. Artificial surfaces were introduced to reduce the maintenance associated with grass. Basketball was invented to make use of gymnasiums that were already built (with wooden floors), and "pro" basketball always uses courts that are made to a specified standard. Unlike tennis - advances in technology haven't shown a need to change the playing surface.