Modern slot machine bonus games

A couple times a year I get dragged to the casino by the in-laws so they can get their gambling fix and I can trickle away $40 on nickel slots to pass the time.
Of course sitting on these machines so long gives me time to ponder how the things actually work.

For anyone that has played the modern machines lately they know that one of the goals is to get to the “bonus” games where the bigger payouts lie.
The bonus games are usually some variation on choosing a person/item/animal via touchscreen behind which lies a various credit amount.
For example there may be several antiques sitting in a gallery and you touch say the grandfather clock and behind it says “500 credits” which are them added to your winnings.

My question is: Does the machine already know how much you will win in the bonus round before you even begin playing?
So even though it appears there are random hidden amounts behind each object in reality the machine knows it wants to pay out 500 so no matter which object you choose it will put the 500 behind it?
Which in turn would mean there is no sense in having “regretted” making a bad choice on these rounds since they were going to place that dud amount behind whatever object you choose.