For something to qualify as money, it must satisfy several key characteristics, one of the most important being general acceptability. Money must be widely accepted by all members of a society as a medium of exchange in transactions for goods and services.
Cheques are not money because they are not generally acceptable as a medium of exchange. A cheque is merely an instruction to a bank to transfer funds from one account to another. Not everyone will accept a cheque in payment - a market trader, a taxi driver, or a small shop may refuse it. A cheque can also bounce if the drawer has insufficient funds, which makes it less reliable than cash. For these reasons, cheques function as a means of transferring money rather than being money itself.
The fact that cheques are used during business hours is not the defining reason they are excluded from being money - many forms of payment have time limitations. The scarcity of banks in rural areas is a practical challenge but does not address the definitional issue. Government issuance is not a strict requirement for something to be money; coins and notes are issued by the central bank, but the key test remains general acceptability.