it is
a country needs to spend dollars on its military
or you end up on the receiving end of an invasion, a la Iraq
seriously
I remember the Iraqi armored corps fortifying their positions with sandbags, only to have Apaches (army helicopter) using their missile systems, to take them out. The pilots were on a military show teasing the Iraqis, for using such an old tactic, against a modern helicopter. The Apache has missile modes, which allows it to fire behind cover, such as a mountain or trees. The fired missile does a steep climb and comes down on top of its target. Generally, when fortifying a tank position, you put barriers in front and on the sides of a tank, which is good for frontal engagements versus armor or infantry. A tactic like that would have worked in the past (when helicopters weren't as sophisticated), but since they were unable to keep up with modern times, they ended up losing tons of equipment like that.