Is there a reason the British omit the article when they "go to hospital"?

Solution 1:

I can't speak for AmE, but in British English there is a distinction between "to school" and "to the school". If you say:

He went to school/church/hospital.

you imply that they went there for 'the purpose for which that place is designed'. On the other hand, if you say:

Jimmy's parents went to the school to meet the headmaster.

He wasn't religious, but he went to the church to help with the flower arranging.

With a bottle of arsenic in his pocket, he went to the hospital to visit his sick wealthy mother-in-law.

it implies that they went there as a visitor and not for the actual purpose of the building in question.

Solution 2:

When we omit the article before the noun, we are thinking of a state or condition, not of a specific place: in jail, in love, in hospital, at university, under fire,

Solution 3:

How we refer to roads is a an example where the reverse is true (in some parts of the US). Brits might say Take the M1 or Take the A1, while most Americans will say take 95 or take 81. In Southern California, however, people say, take the 101 or the 1.