A very interesting list to say the least.

The major component of the mega-corp money saving justification is the consolidation of overhead functions. e.g. finance, payroll, HR, media

At tiny companies, these tasks are either outsourced or done by the c-level employees. As a company scales you need departments to handle these things. A company of 50 people may need 2 HR folks but the tasks for HR can scale (especially with technology) such that if that same company scaled to 1,000 employees it wouldnt need to hire 20 HR folks (maybe just 10 total needed) thus saving 10 heads in HR of salary + benefits + office + IT assets + support. Not insignificant sums.