Direct debit is not the same as debit card. You can pay in physical stores with debit card but not with direct debit (which does not involve a card at all).
As a side note, in some countries, it is actually possible to initiate a direct debit at the POS (since cards sometimes contain enough information to recover the IBAN, mostly for historical reasons), but this has significant risks for the merchant and is usually not worth the hassle as debit card fees are very low anyway.
As a side note, in some countries, it is actually possible to initiate a direct debit at the POS (since cards sometimes contain enough information to recover the IBAN, mostly for historical reasons), but this has significant risks for the merchant and is usually not worth the hassle as debit card fees are very low anyway.