No amount of money will discover long term effects in the short term.

A counterexample from a non-biological domain would be accelerated aging tests of electronic equipment. Could there be any similar approach that aims to do this in pharma testing?

The project management triad doesn’t tell you what is scientifically possible — it tells you what is economically impossible.

Adding money won’t shorten the timeframe here, but shortening the timeframe adds potential risks (and risk=dollars)

You can maybe give higher doses or look really carefully for early signs of something being wrong? But I guess you can't do it as accurately as accelerated aging tests in eg. mechanics.

The project management triad is a spectrum, not three boolean values, and not all of the areas of the triangle are necessarily within the bounds possible choices. (For example, consider how many bids you might expect on a project with a budget of zero)

Marginally speaking, governments are demanding this vaccine at same/lower prices and more accelerated timeline. AZ reasonably sees an associated rise in risk with this, which at the end of the day, is a cost for them.