I think the truck pulled in front of them abruptly & brake checked them, and since it’s so much bigger than the car they were driving they hit it as if they were hitting a wall; it just crushed their car. I’m not sure about the rest; it could be that after the fathers accident, all his possessions & shares were transferred to his brother, and his brother might’ve decided to sell.
I thought the truck purposefully drove backwards and hit them... And of course the scum will need an excuse so it won't trace back to him. Maybe he thought he died in the accident that's why he left him the way he is and even if he wants to make sure he stays dead, further involvement will raise suspicion that they were actually murdered rather than it was an accident.
Also properties.... My aunt passed away without a will and no one will be able to take care of her house so our family needed signatures of her closest relatives, her siblings so the ownership will be transferred (although I'm not exactly familiar with the detailed process since my sis took care of it)... Maybe the same thing happened as well.
This will maybe give you like answers if you’re kinda confused.
1. The truck purposedly hit them - As you can see the masked driver pulled reverse on speed purposedly hitting their car. Obviously that driver is one of Taehon’s dad men so that driver will just escape after the “accident”. So investigators will have no way to determine/trace back to him. He’s a gangster so obvi he has means and connections with police to cover this up and just declare this as an accident/blame on Sejun’s dad night blindness.
2. Taehon’s dad intentionally wanted to kill Sejun’s parents. Since they fled he must’ve thought he will just eventually bled to death. He must’ve not expected he will survive, but regardless his intention is to get the uncle to have the power on decision making. The land that Gin Gyu was eyeing is like a land owned the brothers (Sejun’s dad and uncle) The uncle can’t get it to sell to Gin gyu Bec Sejun’s dad is opposing since they co own the land if one does not refuse of course it can’t be sold. So he just need to make a situation where the uncle will have the sole decision making. (I’m sorry this is a spoiler, it’ll make sense in chapter 43 I think)

I am kinda disappointed because now it looks like the MC’s dad had “Night blindness” and kind of got into the accident for being a bad driver some how the accident itself doesn’t make a bunch of sense they had seatbelts they weren’t speeding…… BUT regardless the father never died- So how did the ML’s dad get his desired outcome if he didn’t kill the MC’s dad. Even if a family member of the MC’s dad takes hold of the shares I don’t know how much right does he have to sell them off especially since they weren’t sold off before and the accident itself and the shares being sold would cause suspicion and foul play to whoever investigated the crime scene. Sometimes these omegaverse dads just seriously lack common sense and are too greedy- the ML is doing an amazing job without his dad and the dad just ms him to have a political marriage even though he’s bonded? Having an arranged marriage when the ML is doing fine on his own to excessive, trying to hurt the son when he is successive and won’t take it well is also a giant No No to me but it is what it is