Not sure which part you were in, but this is just not true in my experience. I've been to Beijing, Shenzhen, Guangzhou, and some others, and Mandarin really is a must if you want to even have a chance of communicating. I can't imagine how I'd function here if I only had English.

I've not yet been to Shanghai, and while I would expect the English-speaking percentage to be a bit higher, it would still likely only be in the single-digits by my estimation.