In the UK this would be done as redundancies with a consultation period and semi-strict laws to adhere to.
In the US it seems like you can let people go for at moments notice with little process - in the UK that looks like what we would call “being fired” generally for cause.
“In United States labor law, at-will employment is an employer's ability to dismiss an employee for any reason (that is, without having to establish "just cause" for termination), and without warning, as long as the reason is not illegal (e.g. firing because of the employee's gender, sexual orientation, race, religion, or disability status). When an employee is acknowledged as being hired "at will", courts deny the employee any claim for loss resulting from the dismissal. The rule is justified by its proponents on the basis that an employee may be similarly entitled to leave their job without reason or warning. The practice is seen as unjust by those who view the employment relationship as characterized by inequality of bargaining power.
[…]
The doctrine of at-will employment can be overridden by an express contract or civil service statutes (in the case of government employees). As many as 34% of all U.S. employees apparently enjoy the protection of some kind of "just cause" or objectively reasonable requirement for termination that takes them out of the pure "at-will" category, including the 7.5% of unionized private-sector workers, the 0.8% of nonunion private-sector workers protected by union contracts, the 15% of nonunion private-sector workers with individual express contracts that override the at-will doctrine, and the 16% of the total workforce who enjoy civil service protections as public-sector employees.”
In the US it seems like you can let people go for at moments notice with little process - in the UK that looks like what we would call “being fired” generally for cause.