Oxford Dictionary says that
When a school is being referred to as an institution, you do not need to use the: When do the children finish school? When you are talking about a particular building, the is used: I’ll meet you outside the school. Prison, jail, court, and church work in the same way: Her husband spent three years in prison.
So, when you say "I go to school", "school" is an uncountable noun & means a general teaching institution.
But, when you say "I go to the school" "school" is a countable noun & means a physical school building.
My question is that:
Do we apply that same principle to the word "supermarket"?
For example, "I go to supermarket everyday" (supermarket here is an uncountable noun & means a general supermarket)
"I go to the supermarket everyday" (supermarket here is a countable noun & means a physical supermarket building)
But in Longman DIctionary, "supermarket" is a countable noun only.