I'm travelling to Germany with a 17 year old, who will be 18 at check-in. One chain hotel I'm thinking of staying in allows 17-year-olds to stay for free, but charges 18-year-olds as extra adults ($50). If I have to pay the $50, I'm better off staying elsewhere. In the USA, I would just ignore these rules, check-in myself and have no issue. But in Germany, will I have to present all our passports and hope the clerk does hassle me for the extra payment?

Thanks, and sorry if I've offended anyone with my practicality.