Every deal carries its own site address, separate from the billing address on the customer.
That matters as soon as the customer and the location are not the same thing: a landlord in another county, a letting agent booking work across six properties, a main contractor with four sites live at once.
Adding one
Add it on the deal record in the sidebar, or when creating the job on the phone.
On the phone, tapping the address opens it straight into maps for navigation, which is the whole point of having recorded it.
Why it is free text
A real job address is not always a tidy postcode. "Third lamppost past the Dog and Duck" and "unit 4, round the back, buzzer does not work" both need to be recordable, because they are what the person driving there actually needs.
If you want structured addresses for reporting, use the organisation record for the billing address and keep this field for the practical detail.