I would not be so forward, with friends or neighbors. Also not for me to use any false detail.  Which gets back to resolving for everyone, by making the phone field optional , and never mandatory,  to complete a sale.    

Thanks Michelle, that's a good work around, but the phone number it requires, needs to be a valid number  not made up. I have tried, "no phone"  but without success. 

No he does not have to " must have " at all. Yes 15 years ago I signed up with one  , but I no longer can use a phone.

My browser is automatically updated, but let's see if its the listing:  You will need to go to buy now, and pressing on delivery instruction causes the " Please enter a phone number " in red  Try this one ;   https://www.trademe.co.nz/a/marketplace/sports/hunting-shooting/archery/other/listing/5751287931 and this one  https://www.trademe.co.nz/a/marketplace/home-living/outdoor-garden-conservatory/garden-power-tools/other/listing/5751388499 and you should get  

Gosh what a funny reply like lecturing, on how to discriminate.  Obviously  identification and fields that are mandatory requiring phone numbers needs to change to accommodate those with a disability or of age, that they cannot use phones. Being constructive, what do you suggest ?  

Pacifying as you suggest, with false information , is not at all proper.  The answer is to make the field optional  and not mandatory, for the reasons already stated.   

And here is example of the mandatory phone number field.

You have correctly identified the circumstances but are wording as assumption. As example  "for courier purposes"  your answer guesses that "you can ignore" because in reality  the buyer has no choice of their own to ignore, rather they cannot complete the sale, other than complete the phone number field. OR give up on that purchase and move to a more considerate seller. And again your missing the detail and inventing excuse , as its not "stated as a term of the purchase in their description " , other than finding out that the phone field is mandatory.  TradeMe need to adapt different ident...

Yes it is a huge problem ,  but is straight away solved by recognizing,  if you could not use a phone, (so for a moment place yourself there )  , that the requirement you are seeing, is not to stop , your right to provision of those goods and services different to those who can use a phone.  The sale of the goods is not to hinge on demanding you are assumed able to use a phone, if you cannot.    

But it is not standard, and should not be expected to be pretty standard by anyone , to be stopped from completing a purchase, if , in the circumstance , one cannot use a phone, or does not have a phone number.