It actually isn't. Often the voluntary separation offers the most severance or is close to it. Everyone left now has a ton more work to do while being paid the same and knowing that you won't be getting a raise or bonus. Everyone is waiting for the next round of layoffs. You also need to be careful that you don't make a mistake that would allow the company to fire you without offering a severance (I know one person who grabbed something from a late-night cafeteria and forgot to pay for it and was promptly fired the next day).

Best to get off of a sinking ship early, since that's when the biggest lifeboats are available.

The people who are left have to do more work and are less likely to get nice severance packages during the next round.

Healthcare + low skilled, low wage jobs (EMS, manufacturing, parcel delivery, warehouse work) are taking a lot of slack out of the employment market

Check out where job gains in the US were in November: https://www.bls.gov/news.release/pdf/empsit.pdf

Healthcare added +32k jobs, the majority of which were ambulance drivers/EMS jobs

Manufacturing added +27k jobs, mainly in chemicals and heavy metals

Transportation and warehousing added + 25k jobs, mainly in package delivery and warehouse work

Business services added +32k jobs

All other sectors remained largely unchanged

I don't think a 50YO radio engineer at Verizon is going to be happy retraining to be an EMS or package delivery courier. Labor, especially older and higher paid (non management) positions, is not in the best position right now despite the record low unemployment rate