Falsely threatening your toddler with taking away their weekends is a "white lie"? Why parent using fear and deception? Why not actually working on helping them manage their own feelings/emotions/needs without punishment looming over them?

All this kind of stuff does is teach them that they shouldn't do "bad" stuff when they're likely to lose something from doing so... which usually becomes "I can do 'bad' stuff as long as I'm unlikely to face punishment for it or as long as the reward outweighs the punishment".

Telling these lies to your kids and other forms of manipulation also usually makes them more distrustful of you and less likely to be open to you when they start to become more socially/emotionally intelligent.

Lying and punishment (or threatening punishment) are both generally counterproductive/destructive when it comes to human parenting and encourage developing troublesome behaviour patterns. It's usually lazy or poor parenting (something that even good parents are susceptible to doing, being imperfect and all), and unfortunately most parents use it as their primary method of dealing with behaviour they don't want. Especially with neurodivergent children, who are affected significantly worse by this form of parenting.

Something relevant is that rewards are significantly more complicated and require a lot more consideration on how they may affect the child's performance based on motivation – too much, too regular, or incorrectly placed extrinsic motivation can have a negative effect on performance when there otherwise would have been enough intrinsic motivation, and you don't want a child to end up expecting an extrinsic reward or relying on extrinsic rewards for motivation. In that case, the lack of a reward may then start to discourage good behaviour (or discourage limiting destructive behaviour). You also don't want the child to tie their personal self-worth to the thing you're rewarding, then they have feelings of shame when they can't meet those expectations, and they become paranoid about meeting them. This is a problem commonly caused by evaluative praise/non-descriptive praise which focuses on outcome rather than the process and assigns a "good" or "bad" label to the result of actions, as opposed to descriptive praise which is neutral and encourages constructive self-reflection.

Two good books addressing issues with deceptive & manipulative parenting and the methods which are beneficial in the long-term are Unconditional Parenting and Punished By Rewards (Alfie Kohn)

In many situations where a child's having an outburst that's negatively affecting others in an attempt to gain something (like attention), it may be better to have them take a break (as in temporarily separate them from the people they're bothering) in a non-punishing way (so not a "time-out" or total isolation/deprivation of stimulation) while staying calm and not speaking/behaving harshly, not lie to them that they'll incur a loss. You may even be able to have a conversation with them afterwards about their emotions and why they feel their actions would get them what they wanted or needed, but sometimes too much conversation can actually have the effect of a reward if your child was seeking attention by doing the negative behaviour, so it can sometimes be more productive to keep your message short and simple – calmly/non-aggressively conveying that this behaviour won't get them what they need. Actively managing attention and making sure it's not used as a reward nor as a punishment can be very hard, you can give or divest attention without even realizing it, but it pays off a lot in the long-term. Kids aren't adult-levels of emotionally mature and have very little impulse control, but they're not irrational or (emotionally) unintelligent either, despite that being the common belief.

Really a lot of these problems with addressing unwanted behaviour stem from the lack of widespread & accessible science-based parental education. For a lot of parents, the only guides they're receptive to are (usually religious fundamentalist and/or for-profit) garbage mommyblogs and Facebook parenting groups, plus whatever their family or friends tells them is right. Most parents are basically winging it with little to no training or education, which is a recipe for a bunch of fucked up and traumatized future adults. It's hard to understand the long-term consequences of your actions if you were never taught about them in the first place, and especially so when contradictory ideas like "punishment/reward is the right way to parent" and "kids are our property and less human than us" is so deeply ingrained in our culture.