Well many corporations are terrible, but there are underlying issues as well (from a US standpoint anyway) such as a litigious society, companies must be guarded in communications around terminations as the employees may sue and any communications will be used in court against the company, also providing "notice" which is different from severance is generally ill advised, I would encourage companies to provide severance packages, but rarely "notice", specifically in a highly sensitive roles like Sysadmin or Dev. as the number of storied around data and IP sabotage and theft are pretty well known, severance softens the blow economically for the outgoing employee(s) while protecting the company.

There are many other things as well