Many courier companies will require the independent contractor drivers who handle driving contracts for their customers - to have an EIN number. Having an EIN number from the IRS shows you have set up a courier business tax number with the IRS.
The IRS website will show you how to get an EIN number which small business courier drivers will need to open a business checking account and file a courier business tax return.
https://www.irs.gov/businesses/small-businesses-self-employed/self-employed-individuals-tax-center
it also protects you from using or giving out your personal Social Security number when you are paid for driving routes and other driving contracts.
When a driver is paid for a driving contract, the company paying you is required to record a tax id number with that payment, so the IRS has a record of these earnings. Having an EIN for your courier business income is preferable to using your Social Security number. see more here
https://www.nerdwallet.com/article/small-business/benefits-of-getting-an-ein
