I could be wrong, but the way I understand the HQ doesn’t operate any “corporate services” that the “operating businesses” can subscribe to, for ex: running payroll, or benefits etc.
I think you’re right. The only thing I’ve heard mention is that Ted & Todd run some of the investments for for subsidiaries’ pensions. I think this is a major place Berkshire could offer something to its acquisitions. I hope that there is some cross- sharing of technology and methods among subsidiaries, but Berkshire is large enough where developing custom technology solutions for payroll would be cheap compared to subscribing to something like ADS payroll. It’s also large enough to really negotiate a good deal on healthcare.
He just wants cash and he wants it so badly, he doesn’t want to even share some of it with his fellow “partners” as dividend 
Eh, buybacks are a superior way to return cash to shareholders as dividends force a taxable event on acquirers and retirees alike while offering no savings on tax rate.