Why does Shopify require a shareholder's SSN instead of a Corporate Tax ID?

[nexgenpackaging]

We are an LLC with a half dozen shareholders.  For every Federal filing we do in the US we are able to use our Corporate Tax ID number for revenue reporting.  Why does Shopify insist on one of the shareholders giving their SSN?   Not only is it uncomfortable to share your SSN, it puts that one shareholder at risk for income tax charges, penalties, etc.  I would think that Shopify is able to manage both consumers selling on their site as well as corporations?  Any assistance would be appreciated.  Thank you!