Chain link fences or corrugated metal sheets or panels at a height that has a survivable drop on the other side will not work. Thick walls or fencing at 25 ft. high isn't survivable on a drop. Illegal immigrants with the goal of breaking & entering are not experts climbers. Only free solo climbers can possibly climb the border walls/fencing free of anti climbing features.
Borders Walls are designed to funnel illegal border crossers to a gate, slow & stop illegals on their tracks. With an effective wall/fencing along with surveillance technology & ground patrols illegal crossing will be much more difficult to cross or penetrate than a barrier-less border. (The White House fencing & surveillance & armed guards, & Gated Communities works in this manner).
Since Ancient times castle walls, border walls has serve to slow down or stop invading hordes for a time to buy time & ready their defenses against the impending hordes. China's great wall, wall guards, wall stations/barracks (camp/bases) & signal towers couldn't be penetrated that's why Genghis Khan Had to go through or was funneled to east inner Mongolia where there was no wall. The Mongols where Superior Warrior & Tacticians, Eastern Europeans & Persians were no match against them as well.
Without a barrier tens of thousands can cross at the same time every minute. Walls prevents tens of thousands from braking & entering (invading) at the same time every minute.
The incentives for illegal crossing is fraud. Unaccompanied minors (teenagers) will get welfare & housing with clubhouse amenities. Anchor babies will get welfare/housing assistance. Accompanied minors will get welfare as well. Illegals use false identities & fraudulent social security numbers. American citizens engaging in welfare fraud or any fraudulent schemes gets charge & imprisoned, but illegal aliens get sanctuary, especially the criminal element as they are not deported.
In the middle east & some Asian/South Asian countries, illegal aliens engaging in capital crimes (rape, murder, smuggling/trafficking (drugs/human), grand theft & robbery) gets executed. Illegal alien gangs robbers/murderers were executed in a middle eastern country using cranes to lift the executed bodies in display for the public.
Until Birthright citizenship, employment opportunities, & welfare/housing benefits are abolished & denied to Illegal Immigrants the way Jordan's current policy is, a barrier wall is necessary. Only real refugees escaping genocides seek refuge in tenth cities Jordan will only provide