A wall doesn't stop those seeking asylum. All they have to do is seek out a border guard and ask for asylum, then they get a hearing. The wall is meant for those who are coming to work without a claim of asylum. We have under 30K asylum seekers at the southern border, even though CBP located over 180,000 people crossing just in May.People see what they want to see, and when Biden said "asylum seekers" they took that to mean them. They're all seeking asylum.
The number of travelers didn't drop much, just the size of the groups.Yes, but it was part of a multi-pronged effort. Guatemala was especially helpful as they'd arrest every caravan leader they could find and seize any traveler's papers who had entered Guatemala illegally. Mexico also rolled out the "You are home" initiative to turn the migrants into Mexican citizens but they were forced to stay in Chiapas or Oaxaca (areas with heavily native populations that most of Mexico dislikes). By 2019, the caravans has essentially ceased to exist.

What happened to the migrant caravans? | CNN Politics
Nearly a year after migrant caravans captured the nation's attention and drew the ire of President Donald Trump, they appear to have fizzled out, marking yet another shift in their ever-evolving immigration policy narrative.
If you try to enforce identical policies on people with wildly different motivations, you're going to get non-optimal results.