For a limited amount of time and they only cover a portion of your income. I know people who were laid off who had to upend their entire lives as a result. As just one example, their kids schooling was impacted as they had to drop everything and move during the middle of the year. One kid ended up getting held back as a result. They also lost of ton of money because they had quickly sell their home.
Anyone working on a sponsored visa has a very short period to find a new job, or they have to leave the country.
Unemployment insurance maximums is below minimum wage in some states (e.g Arizona). In Washington, where I live, it's higher, but would barely cover the typical mortgage payment for an experienced software engineer.
The lack of universal healthcare means that anyone who uses medical services regularly (or has family that does) may end up having to navigate whether or not to find an exchange plan or spend most of their unemployment benefits on COBRA.
Biggest challenge I've seen is with stalled advancement, particularly for people with 10+ years of experience.
That said, those impacts are less severe (for ppl like me) these days as recent layoffs are more broadly recognized as resulting from executive and management failures.
That said, the general lack of a useful social safety net in the US can easily lead to chaos for US-based employees who are laid off.