Because the Mos Eisley cantina did not serve droids and Luke did not want to cause trouble.
In the Mos Eisley cantina on Tatooine
When Luke and Obi-Wan were talking with Han Solo, they were not in a spaceport. They were in the Mos Eisley Cantina. (Mos Eisley is also the name of the city where they met Han.)
i would say "that cantina song in episode 4"
The bar in the first movie where where Luke meets Hand Solo is called the Chalmun's Cantina. It is also called the Mos Eisley Cantina. This is the one filled with all types of universal creatures and that iconic music that will not go away.
Luke and Obi Wan meet Han Solo at Mos Eisley on Tatooine.
Mos Eisley
Of the main characters... Luke, Leia, Han, Chewie, Lando, R2D2, C3PO
He stands on or enters the archetypal threshold.
C3PO is a friend to the ancient cultures of the world. He has befriended the ancient egyptians and the ancient greeks, the homosexual aspects of C3PO's personality is due to the strong relationship he had with the ancient greek warrior Suckis Myballius. C3PO and Suckis Myballius' relationship was unable to work due to the fact that one was a robot and C3PO was unable to efficiently satisfy the greek warrior's sexual appetite. Myballius' army also did not want to fight for a flaming homosexual, so Suckis banished C3PO and they were never together again. C3PO made it to the ancient egyptians where he was made to serve as a slave. During his time in ancient egpyt he had a strong bond with a fellow slave by the name of Shadower Isabitchermun, no one is 100% sure of Isabitchermun's nationality. Pakistani, Lebonese, Greek, Egpytian, Brazilian, Indian, no one is sure but many assume he was Egyptian as he served in Egypt for so long. The pair remained friend's for many years after, until C3PO was finally taken back to serve Luke Skywalker, where he unfortunately was destroyed by the evil Darth Vader. In short, Suckis Myballius and Shadower Isabitchermun were C3PO's strongest allies.
Main characters in A New Hope include Luke Skywalker, Obi-wan "Ben" Kenobi, Han Solo, R2-D2, C3PO, Leia Organa, and Darth Vader.
Luke Skywalker. R2D2 and C3PO arrive at the beginning of ROTJ. Lando is already there posing as a guard. Han is of course there, frozen in carbonite. Leia arrives (in disguise) with Chewbacca and is captured trying to rescue Han. Luke then arrives in his black robes and is dropped into the pit to fight the rancor.
Luke Bryan can drink while a bit. He drinks a lot while travailing on his tour bus.