There are two plots of land. Lets treat them as a single plot as they are beside one another and are part of this story.
The government wants to build a highway on these 200 acres of land
The government, previously bought part of this land for $10K an acre
That's $2.1 million at those prices for these plots in question
All of a sudden, without warning, a businessman from Alberta buys the land for $10M
The very next day this person sells that same land for $16M
This land is then sold to a government agency for $21M
The government agency then sells it to the highways department for the assessed price, $11.5M
There are two explanations.
The first buyer was incompetent that he did not look into expropriation possibilities.
The second buyer was incompetent for buying the land for more than it was worth.
The government agency was incompetent for buying the land for much more than it was worth, especially as it had expropriated part of this land already.
The highways department was incompetent for not buying this land sooner.
The first buyer was tipped off made some money which will (or already has) found its way back to the friends of the governing party
The second buyer also got in this deal and the money, again, either will or has found its way back to these "friends"
The government was complicit, knowing that this was a great way to line their pockets from the public till
There may be more possibilities, but these are fun to think about.