The literal meaning of God's words is what people can readily understand.
That is why the Lord gave a warning not to interpret His words literally, because understanding His words only in their literal sense leads to destruction
2 CORINTHIANS 3:6
6 Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.
Even if it was the custom of the Jews to share from the same dish, there is nothing inherently wrong with that in the literal sense. The Lord's primary message, however, is spiritual in nature.
Therefore, to those who do not know the one true God, the Lord will not reveal the spiritual message of His words.
Instead, He allows them to remain with only the literal meaning that they understand.
MATTHEW 13:10-14
10 ;And the disciples came, and said unto him, Why speakest thou unto them in parables?
11 He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
12 For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.
13 Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.
14 And in them is fulfilled the prophecy of Esaias, which saith, By hearing ye shall hear, and shall not understand; and seeing ye shall see, and shall not perceive:
It is only to His chosen ones, or to those who know the one true God, that He reveals the true message contained in His words
MARK 4:34
34 But without a parable spake he not unto them: and when they were alone, he expounded all things to his disciples