There is a workaround...
Does your company have a MCC? If not, create one, then add all accounts to that MCC. Next, let all "budget orders" go through that MCC. A "budget order" is similar to a purchase order, you give Google the right to spend a certain amount in a certain period.
Having done that, you can use the
BudgetOrderService - method get returns all budget orders. You have to call that service with a login associated to the MCC with the budget orders. And then you're still not there, you have to ask Google for whitelisting (see the highlighted section of the docs).
So a lot to do, but if you already have a MCC, and you've centralized the spendings in that MCC, you're almost there.