Okay, the employer matches social security/medicare on behalf of the employee, you're right I didn't know that and was wrong in my post.
But let's look at some actual numbers. The contribution is 6.2% for social security, and it's capped at $117k for 2014. So the maximum per employee is about $7k a year. The average will be a lot less because of the many, many employees who make substantially less than $117k a year. Merck has 76,000 employees, so let's say they pay an average of $4k per employee in a year, or about $1k per quarter. That's $76k for the entire company.
Given the cap it's crazy to consider social security as proportional to profit for companies making hundreds of millions to billions per quarter.
Then there's medicare at 1.45% without a cap. I don't know what the total wages are for the employees, but I'm pretty confident that payroll isn't coming anywhere close to what profit is like for these companies, and that would be for 1.45% of the total profit, not 35%. I don't see how you can possibly compare this sort of withholdings with the tens to hundreds of millions per quarter these companies are supposed to be paying in corporate taxes.