“Shouldn’t the shipping company be liable?”
That’s difficult when the ship is flagged in Singapore.
Sketchy ownership* (Grace Ocean Private Ltd), Singapore flagged, Indian managed and crewed (Synergy Marine), Danish chartered (Maersk).
*Singapore based Grace Ocean Private is owned by Grace Ocean Investment Limited in BVI, known for its banking secrecy and hiding money for the uber rich. Grace Ocean Private was based in Hong Kong, but moved to Singapore, though Lloyd's reported them still in HK as recently as 2021. You can also be sure the insurance group will not blindly pay whatever the Baltimore Port demands. For example, delays that are not directly attributable to the incident (bureaucratic, labor, environmental lawsuits, etc) won't be covered, nor will many financial impacts. They will also fight over the value of the old bridge (depreciation) and the cost of the new bridge. They will probably get a bid from a Chinese company that will complete the project for half the price of a US company.
And why does that matter? Does being flagged in Singapore make it less liable?