Basically this is a way for a company to downsize older workers (and their higher salaries ) without breaking the law. Its not so much about making it less brutal.
The rest of the workforce is told it's less brutal because those who take severence are about to retire anyway. It simply accelerates that choice.
Legal Requirements
Employers typically offer severance in exchange for the employee signing a General Release of Claims, which prevents them from suing the company for wrongful termination or discrimination.
Review Periods: Under the Older Workers Benefit Protection Act (OWBPA), employees aged 40+ must be given 21 days to review an individual agreement (45 days for group layoffs) and 7 days to revoke their signature.
The federal WARN Act requires employers with 100+ workers to provide 60 days' notice for mass layoffs. Failure to provide notice often results in the employer paying 60 days of salary as a penalty, which effectively acts as a mandated severance