"Report spam" is quicker and easier than "unsubscribe".
Gmail added a popup asking the user if they want to unsubscribe when flagging a newsletter with the appropriate unsubscribe headers, so it must be common enough to warrant Gmail developer attention.
Pretty sure hotmail/outlook also has the same sort of popup for spam reports. I think accidental would be kind of hard with that popup.
Does gmail still insert ads in the free tier? That would be a reason to keep people reading as many emails as possible.
> Gmail added a popup asking the user if they want to unsubscribe when flagging a newsletter with the appropriate unsubscribe headers
Unfortunately close to 100% of the spam I'm flagging causes this popup now :-/
I'm getting a dozen spam a day now on my Gmail account ... I think they're losing the battle.