Random Gumtree Behaviour

I've been using Gumtree a fair bit lately.  I've known about it and what it does for quite a few years, but I've never really needed it.  Mostly I've used ebay or the online Quokka for buying and selling, but I've been impressed with friends' testimonies about how quickly they've got rid of stuff, found bargains, or acquired new housemates via Gumtree.

A couple of weeks ago I was on the hunt for a secondhand TV cabinet.  Since I had an appointment in Perth, I thought it would be the perfect time to buy one.  After being slightly overwhelmed by just how many people were selling TV cabinets in Perth, I narrowed the options down to a short list of cabinets that were NOT in far-flung suburbs. Then I started emailing and texting to find out the dimensions, and if they were still available.

What really surprised me was that out of all the people I contacted, only two got back to me.  A few text messages later, I agreed to meet up with a lady who lives in City Beach.  So I was surprised and a little annoyed that after being in morning traffic for 45 minutes, I knocked on the lady's door only to be told by her teenage daughter that she wasn't home, and that her mum hadn't told her I was coming.  Finally the lady showed up, huffing and puffing, saying she was so sorry, but she'd just been for a walk.  She was a very nice lady with a very nice TV cabinet so I agreed to take it, paid her, she helped me lift it into the back of the 4WD, and I was off.  Now I may have a few screws loose or something, but after arranging to meet someone at a certain time, why would you then decide to go for a walk?

Fast forward a week and I'm back in Perth...this time for a friend's baby shower.  I'd been trawling Gumtree for tub chairs and this time I rang the bloke who had one listed that I liked.  Finally he got back to me, but by then it was too late and I had to go home...minus my chair.

Ok, I know people selling things are not available 24/7 to take queries and it can be quite creepy inviting strangers over to your house to see your goods.  I tried to be considerate with other people's schedules even though I was only going to be in Perth for a limited time.  But if you're selling something, then why wouldn't you get back to potential buyers?  Why are they listing things online if they aren't going to respond to messages?  Surely you have to make yourself a bit more available and contactable if you want to make a sale.  They can't be that serious about selling their stuff then. 

Why invite someone over and then go out for a walk?  That's just weird!

I don't get it.  Please explain...