The can in the OP is one of the worst designs. First off it's a 5 gallon can with no side or bottom handle, so it's unwieldly to handle in the best case. (It's better if you put only about 3 gallons of gas in it, but who's going to do that?) This sort of can should be considered for bulk storage not for filling mowers. The slide spout is easier to control if you take off the child-resistant latch. But then it will pour any time the spout is pushed down, for example if it tips over in the trunk of the car on the way from the gas station. (You're supposed to put the spout on backwards for transport, so it sticks down inside the can, but like only filling 3 gallons that is something no one will actually do).
The ones with a pushbutton valve on the back of the spout can precisely fill mowers and small engines. Though that spout is not good for pouring into cars and trucks.