The upside down hinge is an old one, but as baa-lamb says some are desperate enough to smash off the posts.It does stop the not so desperate, as does welding.
I do tend to agree with glasshouse though, and unless you have cattle in a field then, strictly, a gate is not required. A swinging gate saves a lot of time if you are on horseback, but if you have to get off or out of your transport then L&D (lift and drag) is no great hardship.
An alternative I use whenever possible is what was known in NSW as a Bogan gate. Make the gateway as wide as you like, a loop of wire around the bottom and top of each post then make up the gap with a barb top and bottom, square mesh fencing in between the barbs and droppers if a very wide gateway, but a net stake at each end. You need a neat fit so that one end is fixed in the two wire loops (it could be permanently attached to the gate post) then strain up the other end by putting the stake in the bottom loop and slipping the top loop over the top of the stake. You need to have the infill just the right length and tightening up prior to slipping the top loop over the stake. Perfectly adequate for small stock or arable fields.