"Why wouldn't you travel by main roads?"

Episode 2, Four Marks - Tissaia

Tissaia: "How much for a pig?"
Yennefer's father: "They'll be at market tomorrow."
Tissaia: "Well, I'm here today."
Yennefer's father: "Ten marks."
Tissaia: "How much for this beast?"
Yennefer's father: "Six."
Tissaia: "Four."
Yennefer's mother: "What are you doing?"
Yennefer's father: "Sold. Four marks."

So. What the fuck, Tissaia?

The impression I get with Tissaia is that she is not aware of the different ways cruelty can be interpreted - I would go so far as to say Tissaia thinks she's way too obvious and is doing her best to rein herself in, as if Yennefer is a fellow adult made with laser focus for weakness instead of a traumatized kid to whom she might as well be God. One way this can be read is, "Hey, your life here sucks, no loss right? Look what they're letting me do. Can you believe this asshole?" Tissaia opens conversation degrading his daughter, then haggles him, unnecessarily, for a lower price just to prove the point she's unloved. This definitely does establish that Yennefer's life sucks. It does so by Tissaia introducing even more cruelty into the equation and in every way signaling her new life is going to be even worse.

"Do you know how many people wouldn't blink if you died?"

Shocking that someone told she's a pig to the slaughter thinks it's better to kill herself on her own terms! Clearly, reiterating that no one gives a fuck about her will help with that!

Tissaia is following up telling Yennefer she has no value and something terrible is going to happen with "if nobody loves you live out of spite, god, why do I have to explain this shit", as if the episode up until that point hasn't made it clear to Yennefer there are absolutely worse consequences beyond being lonely and unloved to staying alive.

I feel Tissaia also probably intended a subtext of "jfc I found you and bought you and bound your wounds will you stop being so goddamn needy" and may in fact be trying to be extra vicious to try to deflect from how obvious she thinks this is, but, I don't know, maybe Tissaia is deeply unclear on what happens to pigs after they're brought to market? She seems to never grasp that telling someone they're livestock is even more of a threat than an insult. Yennefer was raising those pigs. She is very familiar with keeping things alive that you plan to butcher later. Like I said, it seems like Tissaia knows what she means (you were being kept like another animal, doesn't that suck? don't you want to be more?) and so is completely oblivious to any other way Yennefer might take it.

Yennefer: "You should've let me die. At least I had control over that."
Tissaia: "Oh, that's adorable, piglet. You weren't taking control. You were losing it."

By all appearances Tissaia does not understand exactly how badly she terrified Yennefer in the first place. She's treating this like a tantrum because Yennefer's mad Tissaia was mean, not a reaction to being completely at the (apparently nonexistent) mercy of someone and being told things are only going to get worse. The very fact someone's come out the other end of a suicide attempt still saying they want to die suggests that it wasn't a temporary panic. (Though it does raise the possibility it's not that Tissaia is unfamiliar with suicide attempts but instead she's seen enough where they also wake up and beg to die for that part to also seem normal.)

I think there's also an element that although Tissaia knows Yennefer doesn't understand the specifics, to her it's obvious that the tower is an improvement. Yennefer trying to kill herself the moment her life gets better, just because Tissaia, what, didn't read her a bedtime story or whatever you're supposed to do with children? (I also think Tissaia legitimately does not know what you're supposed to do with children, and so even when she can tell somehow this isn't working, she doesn't have any clue what else to try.) But in the farming metaphor a piglet just means you have to spend longer fattening them up.