"Far behind Chrome" should never be used in a sentence. Ever. Chrome releases up to 40 new "standard" features once every two months, many of them are just internal Chrome APIs with a "standards spec" in the form of a draft.
Specifically for WebRTC. It was shipped in Chrome 23, in May 2012.
Guess what? Here's the timeline:
- In 2010 Google buys a company called Global IP solutions with some proprietary tech
- In May 2011 it opensources this tech
- In October 2011 publishes the draft spec
- Just 7 months later ships it enabled by default in Chrome
Do you know when the final stable spec arrived? In May 2018, full seven years later after Chrome enabled it by default.
That's why Safari had it implemented since September 2017, because the spec was finally in a proper shape.
No idea why Firefox rushed headlong into it though.