Why would I get a food scale?

I've already got a 1000x0.1g digital scale.

And I don't shop at brick and mortar places. I guess I could call companies and ask them what their components really weigh.

"Hey Deda, what do your bars weigh?"

"They weigh 209g, just like on our website."

"No, seriously, how much do they actually weigh?"

"Alright, off the record, they're actually like 260g."