[onion2k]

There's no evidence that data motivates people to start doing anything. There's plenty that shows data helps you continue once you've started (if you're succeeding, otherwise data works as a negative reinforcer), but if you haven't started yet, additional data won't help.

[kayhi]

I can only say from personal experience, but data has certainly helped motivate people in my life.

Examples:

Data on why saving earlier for retirement is a good idea.

Data on why on being overweight is not good for you.

Data on why smoking looks to increase your risk of cancer.

In these instances people didn't know how 'bad' there situation was and took action.

[bsbechtel]

There's plenty of evidence that shows those signs on highways that show you your speed cause you to slow down.

[onion2k]

There's evidence that the threat of punishment for not slowing down makes you slow down. The signs act as a reminder of that. If it weren't for the law, would many people who are already speeding pay attention to the signs? That would be an interesting thing to test.