These are most likely group life policies where the employer pays the premiums for a base amount for all employees. Since there is no charge to the employee for the base coverage, most would accept the coverage.

If the employee base changed it could end up being unrepresentative of the broader population, but it's hard to imagine what that might be. Healthier people quit? Healthier people left Indiana? A competitor insurance company signed all the healthier groups?

Big employers in the US offer group life insurance to their employees without the need to opt in. Of course they have opt in add ons to increase the coverage, but in any case if you are employed and you die (knock wood) the insurance company’s phone will ring.