It relies on HTTPS, which relies on certificates telling the browser that the website is what it claims to be, which relies on a list of trusted root CA certifi

It relies on HTTPS, which relies on certificates telling the browser that the website is what it claims to be, which relies on a list of trusted root CA certificates installed on your computer, which the company controls. Most companies will install a trusted root CA cert that is themselves onto employee computers (otherwise you'll get SSL errors when accessing internal HTTPS pages since they're not signed with those public root CAs).