Someone on the packing team must have been sloppy again, or the instructions for enclosing an appropriate cable were missing.
You do not have to buy the cable yourself. On the contrary, it is clearly regulated by law, see below.

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Digitec (or any other Swiss dealer) is obliged to supply electrical appliances with a Swiss plug. If the appliance is supplied with a foreign plug, a suitable replacement cable should be supplied if the mains cable is pluggable or alternatively, if the mains cable is permanently connected, a suitable adapter should be supplied.

If the appliance is delivered without a suitable plug, complain to the customer service and insist on a cable or an adapter, free of charge.

Info Digitec --> https://helpcenter.digitec.ch/hc...
Point 1 --> https://www.esti.admin.ch/de...