Who notices, and why
The owners who value Arabic most are often the ones who sign the cheques. A second-generation owner of a contracting company in Al Ain may read English well but prefer to discuss a corporate tax position in Arabic, where nuance is easier. Government correspondence, many supplier invoices and some contracts already arrive in Arabic.
A firm that can move between both languages without making the client switch gains trust quickly. A firm that answers an Arabic WhatsApp message with an English template loses a little each time.