I think there is a huge difference between build a wall or secure the border. Ask the Israeli’s why they built a wall. Ask the Chinese why they built a 13,170 miles long wall. The US-Mexican border is only 1989 miles. (Perry said 1933 in debate).
A wall works 24 hours a day along every inch of the border. Manual patrols along every inch of the border 24-7 is a big expense for ever, versus one time expense of building the wall. Perry’s idea of securing border is manual patrols and surveillance planes. Impossible to cover every inch 24-7.
Walls are force multipliers.
But they didn't build a wall along their entire border.
There is no wall along the River Jordan, where it forms the border.
Yet, that border is still "secure".