|The itemized deductions apply to personal, non-business expenses (more or less) that Congress has decided shouldn't count as part of your income, like charitable contributions, mortgage interest, real estate taxes, medical expenses, and so on. I say more or less because some employee business expenses, like job hunting, are expenses you had to spend in order to get or keep a job, but their associated with being an employee, not a business owner.|
The idea of the standard deduction is that everybody has these sort of expenses, and it would be a lot of work for hundreds of millions of people to keep track of all that, so we get a standard deduction which is meant to be as much or more than the itemized deductions would have been if there were no standard deduction, so most people can just take the standard deduction and not bother keeping track of the itemize stuff. The people who do have more itemized deductions than the standard deduction will list them on Schedule A.
Business expenses on Schedule C are a whole different category. You get to deduct every single sheet of paper and every mile driven from your business gross income to find your business profit, before your business income ever finds its way to the 1040 form. You can take the standard deduction and still deduct that dollar you spend on a binder clip for your notary business, but you deduct it on Schedule C, not Schedule A. Sole proprietor businesses always list their business expenses on Schedule C, whether the taxpayer is filing Schedule A or not.