My use of ethical here is strongly tied to obligation. e.g., it is kind to give money to a person, but not unethical if you chose not to especially if you can't afford to.
The way I understand you is that it's kinder/more sympathetic to provide a greater severance. This part I agree with!
Severance is not free, though. Increasing it will either cost Uber more heads or greater risk (and more heads later). I'm repeating this question: Is this not unethical to the retained employees?
Providing a former spouse with alimony money is not generosity. Neither is providing a former employee with severance money generosity. In both cases, the ethics are incredibly obvious.
The fact that alimony is required and severance is not is simply a matter of a corrupt (US) political system. This system leaves it to individual CEOs to act ethically (or not) and the public to judge them.
We can improve the ethics of tech companies by holding them to account for how they behave. One way to do that is judging their behavior during layoffs.
Separated [Airbnb] employees will receive 14 weeks of pay, and one more week for each year served at the company (rounding partial years up). The firm is also dropping its one-year equity cliff so that employees who are laid off with under 12 months of tenure can buy their vested options; Airbnb will also provide 12 months of health insurance through COBRA in the United States, and health care coverage through 2020 in the rest of the world.