Having worked for Amazon before I'd say that's a fairly safe assumption.

Sounds more like experienced than cynical to me. In my experience, job descriptions and even the answers you get during interviews are not so much outright lies, as aspirational fabrications you have to take with a grain of salt.

I'm guessing you haven't worked for Amazon.

Job descriptions are forward looking statements; the position may be entirely different.

Here are some of the many possibilities:

The service has poor uptime and you're on call every weekend.

Schedule pressure or poor management means that you're asked to come in on Fridays "until the next release".

The reduced-hours position was sponsored by a VP who has lost interest or left the company. Your direct manager has deadlines to meet and pressures you into working full-time.

"Foresight is often mistaken as cynicism by those that do not have it."

Assuming that Amazon is a profit-maximizing corporation that will fully exploit it's human resources to the extent possible, and that forward-looking but non-binding statements cannot be relied on to limit that might be called cynicism but to me it looks a lot like realism.

Amazon became big on lies, and in fact is in the news frequently because it continues to do so.

Corporations exploit the benefit of the doubt. It mustn't be extended to them.

I'd say it's evidence based skepticism