Some locations direct wire is perfectly fine. Some locations prefer that you attach a cord to the DW and plug it into an outlet.

Hard wired with nm cable has been the industry standard around here since they were invented. Only recently have contractors been installing receptacles for them. I usually installa duplex under the sink with one side switched and the other hot all the time. One for the dw and one for the disposal.

If the dishwasher is right next to the sink, I use a cord and install a half hot receptacle under the sink. One side switched for the garbage disposal to plug into, the constant hot for the dishwasher.

If it's not right next to the sink I stub out a wire on the rough in and then direct wire it. If it's direct wired, a breaker lock off is required.

Almost every dishwasher on the market today is cord-and-plug connected. Some people conveniently put the receptacle for the dishwasher under the sink but in other times it's behind the dishwasher.