let (one) off easy
1. To give one a very mild punishment or rebuke relative to the wrongdoing. Considering he completely destroyed Mr. Smith's hardware store and dang near killed a few people, I'd say they let him off easy with just 3 months in jail. I was expecting her to scream her head off at me, but she let me off easy.
2. To expect or demand less from one. Everyone's been letting her off easy since the accident.