You can't have two partners in a transaction following different sets of laws. That's why contracts routinely specify a jurisdiction. Otherwise you couldn't eve

You can't have two partners in a transaction following different sets of laws. That's why contracts routinely specify a jurisdiction. Otherwise you couldn't even agree on a court to hear your case. In B2B transactions, there are often international standards. Even where the supplier's location is set to be the relevant jurisdiction, this only follows from the assumption that a purchaser of industrial goods tends to have the experience to navigate foreign law. This cannot be assumed for consumers.