A restaurant with 300 reviews at 4.7 stars will out convert a competitor with 40 reviews even when it ranks one position lower. Reviews are both a ranking factor and the last thing a hungry customer reads before tapping directions.
Ask at the right moment
The best moment is right after the bill is settled and the guest is still happy. A QR card on the receipt tray outperforms any follow up message we have tested in Thailand.
Reply to every single one
Replies are indexed text on your profile. Mention the dish, the neighbourhood, and the service naturally. It reads as care to customers and as relevance to Google.