As much as possible i won't give any personal documents or ID online especially on today's world. But for trusted sites or company, i don't mind giving especially if it's needed to confirm your identity (still bother me though). One example is on our bitcoin local exchange, you need to take a selfie with your ID to increase the amount of money you can cash out. (i still don't trust anybody)
Identity theft is the most common cases here in our country or maybe in some other countries too. People just need to be careful.