When we talk about staying somewhere, we use the preposition "at." (I am staying at the bar).

Question

If we talk about going somewhere, we use the preposition "to." (I am going to school).

Why are we allowed to leave those prepositions out when we talk about home?
I am going home.
I am staying home.

I got asked that question this week and was stumped. Is the answer, "just because?"

Answer 1

indeed, it is 'just because' .... one of the irregularities of the English language, in some countries, 'I am going to home' is actually common

Answer 2

Actually, after a little searching, I found an answer that makes sense and fits even the dictionary.

In that case, home works as an adverb to mean "to home" or "at home."

Answer 3

That sounds right. I've noticed that the words that came into modern English from middle or old English or earlier have these little quirks.

http://grammar.ccc.commnet.edu/grammar/prepositions.htm
This is an extensive discussion about prepositions - what to use, when to use them, when not to use them.