I only use US Postal MOs for items worth of any value, say more than you'd like to or would be willing to lose. Sometimes I take checks, if the item isn't of too much value. Sometimes I wait for the checks to clear, and sometimes (like if I see the person has been posting here for years) then I'll ship it right out. So always, ALWAYS search on the name of the person allegedly buying the item and see if they line up or appear legit. NOTE on other sites, non-actie people have had their accounts hacked and swindlers have tried to buy items under that other person's name - but shipped to their own address (often fake or transient) - using bogus payments (Zelle).
IMHO if you aren't going to use PayPal a lot - I wouldn't bother. Also note that when using PP 'Fireds & Family' to avoid fees - you don't get any purchase protection, Unfortunalely online - all over sporting and other sites!!!! - too many are being ripped off by people using Zelle payments - so BEWARE!
To me, US Postal MOs give you and the Buyer assurance, as you can verify the MO by calling the automated USPS number. This tells you 'where' the MO originated, so if you're shipping it to AZ but the MO was originated/purchased in MA ... yeah, I'd be more than a little suspect, LOL! Plus as a Seller, you can verifiy the MO water marks, the colored threads and other security features that are built into them.
Just my experience ...