You’d be surprised just how common ‘breaches of contract’ like this are, especially among SMEs.

If the supplier knows that the customer has a tendency to pay invoices EOM +35 rather than EOM+30, it’s not worth the cost to pursue legally - especially as doing so would risk them losing a client.

The first secret of business is to collect money as quickly as possible, and avoid paying out as long as possible, to profit off the arbitrage.