Age limit restriction for risky products is widely implemented as an instrument to improve public health. To study reasons for vendor (non-)compliance this 2 (underage vs. adult consumer) × 2 (low vs. high profit) field experimental research was conducted. Trained mystery shoppers conducted 218 alcohol purchase attempts. ID checks and compliance were significantly higher when financial profit was low (74% ID checks; 67% compliance) compared with the high-profit conditions (26%; 18%). There were no significant differences between the adult and underage consumer conditions. The motivation to comply appears to be the crucial factor, and enforcement needs to be intensified.