They are capable. Developed countries are still below the upper limit of what they could borrow. You can see this in the fact that long-term interest rates ar

They are capable. Developed countries are still below the upper limit of what they could borrow. You can see this in the fact that long-term interest rates are so low. If people were running out of patience for government borrowing you would see long-run rates spiking. While debt levels are high, they are not unprecendented. US debt/GDP is 105%, which is far below Japan at 220%.