Why doesn't Twitter and Google API documentation encode ampersands in URLs?

Question

I have read I should encode my ampersands as & in HTML.
However numerous code samples from respected companies somehow forget

Answer 1

Two different contexts here.

1. Within the context of a javascript href, the & is just fine and should not be encoded.
2. In an HTML link the & is forbidden and should be escaped.

In the HTML link context an HTML character entity will be decoded before the address is passed to the HTTP process; a URL-encoded character will not, as the server can read it directly.