Amanda Bynes -- Strange Night in Hollywood ... Ends with a Chauffeur

Amanda Bynes had a late night in Hollywood, but instead of a nightclub ... she was at Starbucks -- and, more importantly, she did NOT drive home afterward.

Amanda spent more than 3 hours sitting inside the coffee shop ... talking on her phone and listening to music on headphones -- before finally leaving just after 11PM PT.

A Starbucks employee unlocked the front door to let Amanda out of the store -- but with her face fully covered she had to be led, very carefully, to a waiting SUV.

Amanda got in the back seat.