All of this. I'm in non IT tech and personal email is still forbidden (like Gmail and yahoo are blocked on my laptop forbidden.)Many companies don’t allow confidential information to be sent to personal email accounts for security reasons. These companies often make a blanket rule not allowing use of personal e-mail. Tech companies, some banks, and healthcare (sensitive personal information), defense and gov’t are orgs I’ve come across in the past that don’t allow use of personal email for business use. Imagine a tech company, for instance, having employees sharing information on gmail.
It’s probably because you’ve had hourly jobs. Many salaried jobs have an expectation of off-hour work. They also often come with flexibility and comp hours to not make it overly burdensome.
Also, it's a multinational company. So a 7pm email could be from India, and I will wake up to emails from Europe. Not urgent, but it is sometimes nice to be mentally prepared for what's coming during my business hours.