Although MIL does has some influence but not to that extent (in general) you are saying. DIL is member of family need to respect MIL but there are always things which decided been couple.
People make career decisions, on base of what suit them best not on base of whim of one person.
If one marry is settled businessman there would less mobility because:
He is well settle in business at the place and could not take away business with him to different city or location.
Since he is making good money, might not need wife to work thus not willing to compromise due to wife’s career.
But if you are marrying a young professional.
He need wife to contribute at least fews years until stabilize.
Better understanding career requirement and willing to compromise for good of family.
I can understand that these problem could arise to certain extent if one is working in Pakistan, as family mostly have secure house, one person income could feed the family, cultural issues.
But working in US even if MIL does not like, she has no choice but to give way because of environment pressure and Son himself would not support her beyond the certain level.
On other side religiously speaking, according to Shariah Parents are son’s responsibility DIL has no obligation towards them. On other side we would encourage wifes to help husband to fulfill his duties, but strictly speaking it is not DIL job.
I feel that kind of negative thinking might be holding you back, it is better not to worry too much find a good professional person matches your personality and family outlook (I am sure there are many ).