For those who don't mind making a special trip in person, that's fine. But in my opinion it isn't being lazy if you favor a transaction method that accomplishes the same result with significantly less effort... that's just being rational.
I see where people are coming from who just pay in person to start with and don't understand the gripe with that, but it starts to be a real PITA when you try to pay online first. WU gives you every indication that you can send money online, when in reality, it never seems to work. So imagine this: you go through paying online first thing in the morning, no big deal, send the payment info to the dealer, and think you're done with it. Then WU reneges on that after they sent you the confirmation and your bank approved. You get in the car after work, swing by an ATM to get cash, go to the grocery store, carefully fill out a form by hand, wait in line, hand the form to the guy who proceeds to type in what you just wrote at about a quarter of the speed that you could have typed it, then they print things out, you sign things, etc., the fees end up being higher than listed online, so you don't have enough cash and have to pay with debit and incur the fee anyway, all after a long day at work when you thought that you had taken care of this hours ago. Plus, you go through paying with the same damn card that you tried to pay with 10 hours ago. Then you send a clarification email to the dealer saying to ignore the previous info and take this new info, etc. How is that not a pain in the ass?
Sure, if the biggest hassle you have all day is inconvenient payment logistics, that's not a bad day, but when you buy 95% of non-food items online, and are used to paying for things securely and cheaply with the click of a button, having to jump through all those hoops gets to be very irritating. If only people wouldn't be dumbasses with paypal and you could use that everywhere...