lit. "Why don't they eat meat?" (said by Emperor Hui of Jin 晉惠帝|晋惠帝[Jin4 Hui4 di4] when told that his people didn't have enough rice to eat)
fig. (of people from higher class etc) to be oblivious to other people's plight
Definitions (Wiktionary)
phrase, sarcastic
Describing an impractical, ridiculous and often arrogant advise from someone uninvolved: If they have no bread to eat, let them eat cake.
Examples (粵典–words.hk)
Cantonese
何不食肉糜？
何不食肉糜？
ho4 bat1 sik6 juk6 mei4?
a quote of a fatuous monarch of Jin Dynasty, used nowadays to satire a statesman is oblivious about the political reality; literally: why do the peoples not eat minced meat when there is famine?