>after all, it is "their time" that they're paying for
On so many levels, it is not. Even if you're being paid for time, people don't "own" your time or shouldn't be allowed to "own" your time. Ultimately you own your time, they should pay for the privilege to nudge or direct your agency during that time. You should always have agency within that time to refuse to work or do whatever, otherwise we're on paths back toward slavery.
On another level, most employees these days are salaried. Businesses adopted this for several reasons but the primary reason is its a beneficial reduction of labor costs in most cases. Paying employees salary not only makes labor costs more predictable (one argument) it sets a cap on the labor expense to try and maximize work within. Under a salary model, you're really paid for function not time, even though employers want to conveniently, to their advantage, choose when they want to view you as a functional or time based cost within that salaried definition. If you're salaried, there's almost no argument for your "time" which is why most salaried employees have infinite queues of uncompletable tasks stacked on them whilst hourly employees are often scrambling just to find tasks to do, depending again on the context.
On so many levels, it is not. Even if you're being paid for time, people don't "own" your time or shouldn't be allowed to "own" your time. Ultimately you own your time, they should pay for the privilege to nudge or direct your agency during that time. You should always have agency within that time to refuse to work or do whatever, otherwise we're on paths back toward slavery.
On another level, most employees these days are salaried. Businesses adopted this for several reasons but the primary reason is its a beneficial reduction of labor costs in most cases. Paying employees salary not only makes labor costs more predictable (one argument) it sets a cap on the labor expense to try and maximize work within. Under a salary model, you're really paid for function not time, even though employers want to conveniently, to their advantage, choose when they want to view you as a functional or time based cost within that salaried definition. If you're salaried, there's almost no argument for your "time" which is why most salaried employees have infinite queues of uncompletable tasks stacked on them whilst hourly employees are often scrambling just to find tasks to do, depending again on the context.