GMAT Sentence Correction (SC) | Re: Among lower-paid workers, union members are less likely than non union

Among lower-paid workers, union members are less likely than non union members to be enrolled in lower-end insurance plans that[ impose stricter limits on medical services and require doctors to see morepatients] ,and spending less time with each.

What is VERBing"spending " intended to modify in this sentence? Does the VERBing modifier modify the preceding clause in blue bracket[] ?