prepositions - Is it so bad to say "A cafe is at the corner"?

My grammar book says it's "There is a cafe at the corner" but can't say "A cafe is at the corner". Is it really so? I feel that the rule is prohibiting free ways of expressing things.

[Edit] It seems like my careless switching words made confusions and problems. I'd like to go back to the original sentences: "There is a restaurant around the corner." vs. "A restaurant is around the corner."

Maybe 'can't say' was too much and I should have said 'don't say', my grammar book is written in my native language.

So, now I understand that people usually say "There is a restaurant around the corner" in a day-to-day conversation, This is the common way of saying, but in a novel you might also find "A restaurant is around the corner", or you can use it when you are giving a direction.

So both are grammatically correct, but the nuance is slightly different and not really convertible each other. I hope I got this correct.

Answer

EDIT to Add:
A cafe is at the corner is a perfectly fine English sentence. Even The cafe is on the corner is fine--even if you have never heard of this cafe before. Someone can tell you The cafe is on the corner.

Origial answer:
This is an arbitrary rule that is limiting your ways of expressing things. Both sentences are fine. The use of "there is' is the so-called existential construction. It puts a "dummy they" in as the subject and moves the real (or "logical") subject of the verb to the predicate side of the verb to be.

As the wikipedia description says, this construction is used to refer to the presence or existence of something, from There is a God to There is a turd in your commode.

So, "There is a cafe at the corner" declares the existence of a cafe at the corner. However, in a description of a town, A cafe is at the corner works as well. Either one works fine when giving directions, although the existential construction may be more common.

One can also say Here is a cafe at the corner and, again, There is a cafe at the corner, showing that these uses of there and here are deitic, which just describes something from the place in space of the speaker. "There" would mean "over there at that corner" while "here" would mean "right here at this corner." Note the change from the determiner the to the deitic or demonstrative pronouns that and this, which both also reference the cafe from the place in space of the speaker.