I think 16 is a good age to start driving, but I also think it would be good to have a law in place that would limit young drivers to driving with an adult passenger (25 years or older) present until they are 18. There are just too many potential distractions for inexperienced drivers, especially here in the Bay Area where there is so much traffic.
It should be dependent on the individual because high school kids are all different. The criteria should be based on the student's grades and judgment, so a student with good grades and who has never been in trouble should get the opportunity to drive earlier than a student with poor grades and a history of getting into trouble. Criteria like this would also motivate students to do better in school and make better life choices.
Beer garden/taphouse owner
It should be at least 18. I've read legitimate scientific research studies that show a growing child's brain is not fully developed until they are at least 21, and that even between 18 and 21, there is an enormous change. I don't think kids should be driving at 16.
Front desk attendant
The age should be 18 because it is not until then that teens are legally responsible for themselves. They are likely to act more conscientiously once they face real consequences for their actions.
I don't think teens should be legally able to drive until they are legally able to do other things, like vote and drink alcohol. It doesn't make any sense that a teen should be able to drive a potentially lethal weapon at a much younger age than they can drink, smoke or vote.