I was just curious. I looked up the first two homes in that second link and realtor.com is saying they are "Off Market"
When the public cant get the information it is due to MLS having exclusive rights to "their" information. More or less they limit who can publish sold prices to themselves.
Both homes in the second link were listed on MLS (realtor.com) and now showing off market. Disclaimer = *LOL* ALL state/local MLS boards work independently from other MLS boards, so I am only taking a reasonable guess here as to the "why" without spending my day trying to figure out the state of Utah.
Chances are very good if you go to the individual "county" tax websites in Utah you may be able to find out actual selling prices as taxes are public information in almost every state. Last sell price/market value is normally attached to the tax.
Ps!!! Yes, it looks like that is what is happening. I did a search in Utah based on your links. Every "sold" house is showing as off market on Realtor.com.
The only way to avoid putting a "Sold" price in there is change the listing status to "Off Market" when it sells instead of "Sold" then they get to "hold" the information to themselves instead of sharing it with the public. Person with the information wins, always, including against Zillow.
But I can guess it will only be a matter of time where they will lose the battle, but who knows... and again, disclaimer = I only briefly looked at this, this is my best guess without spending the day on it, though I find it fascinating. As our local MLS used to try to prevent sold information from coming out, they lost the battle a long time ago. But maybe not sharing vs county information... cant remember.
Here is one example for a county in Utah to look up property information =
https://www.washco.utah.gov
Scroll down, click on property search, you only need one line of information to look up a property. Most counties have websites like these.