(Wikipedia's article on tax incidence claims that employees pay almost all of payroll taxes, but cites a single paper that claims a 70% labor / 30% owner split for corporate income tax burden in the US, and I have no idea how or whether that translates to payroll tax burden or whether the paper's conclusions are generally accepted.)

There's no consensus on the incidence of the corporate income tax in the fully general case. It's split among too many parties.