system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Almost all the droids we've seen are no larger than an ordinary human. Are there instances where a droid is, say, the size of a ship? If not, what is the reason for the limit?
gpt
I disagree that almost all the droids we've seen are no larger than an ordinary human. 

Droids are generally built to sizes according to their usage. Those that are built to interact with humans are built around the same size as a human, which makes perfect sense. So R2 units are much smaller, and information carrying mouse droids even smaller.

But there are also bigger droids. While most of the CIS' forces during the clone wars were standard battle droids, there were also the larger and more intimidating heavy battle droids, commando droids and Magna droids built at the larger end of the humoid scale (think wookiees or tandoshan sized) to intimidate. And of course even larger droids, such as the Spider droid or the huge seafaring droids seen in the assualts on Mon Cal and Kamino, the NR N99 droid tanks, and the Vulture droids.

So while most of the droids we've seen have been around human size for ease of interaction, it's by no means close to all.