I am sorry to hear that you had a difficult time despite knowing what your mom wanted.
You bring up an important issue in end-of-life care.
The cornerstone of ethics in the United States is autonomy / independence - patients are encouraged and asked to participate in decision-making regarding their wishes. Thus, we have to respect patient's liberty to make decisions that may be not congruent with our own ideas or clinician's recommendations.
But - and like everything in healthcare - this has become much more complicated. To enforce autonomy and liberty, patient-centered care with shared decision-making was introduced more into the medical community. Patients and their families are often lay people when it comes to medical decision-making but need to make decisions that will have impact on their life, quality of life, or even end their life. The idea is that the patient trusts the provider who also provides a recommendations - which should include considerations about what is in the patient's best interest.
Nowadays, with our growing arsenal of technology and "advances", we can easily border on futility. When the "highest" goal is to maximize the life-span, aggressive interventions and treatments are often chosen even though the outcome may be negative and leads to "suffering". A patient has the right to "suffer" if that is what they decide to accept and to go through in order to gain more time. They are allowed to sacrifice comfort for the sake of more time but it is important that they understand this implication.
Physicians can not be forced to provide futile treatments. After all, many interventions are medical orders and a physician has the right to "not offer" this treatment if the patient is not a candidate because the risk is too high or the outcome negative. Examples are surgeries or heart catheter interventions but could also include dialysis. Patients accept more easily when the surgeon or cardiologist says that the risk is too high and that is not an option because it would most likely result in death. That option is not available and thus patient autonomy does not include to choose a futile options. The same with dialysis - only that patients and families have a hard time with that decision. Nowadays patients who are 90 year old undergo dialysis to extend their life but if a person has other comorbidities, the nephrologist may not offer this treatment and refer to medical management.
There is also technology like high flow oxygen, which was thought to be a bridge until a person gets better or dies. But I think nobody really thought about the consequences of this device. When offered to end-stage COPD or similar patients who are so sick that they cannot come off but also do not wish to be trached and live on a ventilator - there is no place for them to go. They "live" in the hospital, which is not the same as home. Lately, I heard more often "if I had known that this is not like regular oxygen and I cannot go home with this - I would have not wanted it".
There are a lot of dilemmas all around.
As a palliative care nurse, I have no "agenda" - my goal is to provide information and care to help patients to live best with a serious illness. There is a huge grey zone where patients do not want to have pain for example or shortness of breath - but also want to be a full code - and though are limited in what can be realized. But it is not my place to pressure somebody into a decision or coerce them - that would take away the liberty in decision-making.
Nurses feel different about suffering than physicians, which is researched. Nurses care and have a hard time when patients suffer "needlessly". Patients and families on the other hand often have their own agenda and are not up front. We see a lot of problems related to not being able to cope with death and not being able to face "loosing somebody" - which ultimately can lead to requests for futile care.
As a palliative care nurse I also have a responsibility to realize when the patient asks for palliative care in the sense of "hospice" but this decision is driven by not understanding ones choices. There are cases where nurses or physicians request a palliative care consult because "the patient does not want any treatment and is ready to die" indicating they respect autonomy but the patient is not competent to make this decision due to mental illness or otherwise incapacitated. Or the patient clearly does not understand that for example life with dialysis is possible or that people can live at home with tube feeds.
There is a lot of room for conflict and friction at the end of life that can make everything more stressful for everybody.
Here is a good article:
What's the Role of Autonomy in Patient- and Family-Centered Care When Patients and Family Members Don't Agree?, Jan 16 - AMA Journal of Ethics (formerly Virtual Mentor)