Underground direct burial cable has been around for at least 50 years , that I know of
Local code decides if it can be used, or must be in conduit
It is quite common, even in high voltage applications
I remember putting in direct burial cable for a 6200v line on airport runway edge lights over 40 years ago
If you have underground utility power to your stick home, very likely it is direct burial, the Conduit is only ten feet on each end , the pole and the house, your power was cable was direct burial, for the whole run from Pole to house with the start and ending phasing thru conduit to protect it above ground
