It all depends on the person and how impaired their mental faculties are. Some may think that a few drinks won't hurt them and they will be fine to operate their vehicle. Others just might not care about what they do and decide to drive. Everyones system can handle some alcohol but the limit of how much varies or differs. People who choose to drink beyond their "safe" limit can harm themselves and others. Impairment of the mental faculties is a big reason why people drink and drive. They are not in the right frame of mind so they are not making smart, safe decisions. I hope this answer helps you. Best of Luck!