At the end of the day it's the sellers prerogative what and what not to take for payment method, and if that doesn't suit the buyer either party walking from the sale or bending their preference.
I get the utility and value of doing cash transactions, but I usually prefer PayPal myself. With friends and family paypal there are no fees and it can't be reversed.
I've worked with some people that insisted on cash and many were fine with PayPal f&f.