Lovely! They found I have a tumor in my kidney!

[spamforbrains]

Just want to point out that getting MRI(s) as part of a basic physical when nothing wrong is suspected is (in general) a dubious idea.

For every situation in which something potentially worrisome is caught early, there are plenty more where harmless anomalies are uncovered, leading to more tests and invasive procedures which can cause harm in themselves.

I see plenty of biopsies of enlarged mediastinal lymph nodes with old granulomatous inflammation (not metastatic tumor as was suspected/had to be ruled out), and oodles of benign thyroid nodules that were only found because someone had imaging studies for another reason - and protocol demanded a needle biopsy because the nodule(s) were at least 1 cm in size.

Although it would be a lovely personal income booster if Obamacare mandated a set of MRIs periodically for everyone

Not just MRIs- physicals, period. Getting "checkups’ when you have no symptoms is rarely a good idea and have more or less been dropped from any evidence-based guidelines. The docs love them because they make money off them, but the patients don’t benefit.
Here, the OP is going around saying this a great thing, but most likely if the MRI hadn’t been done the tumor would have started to cause some flank pain in a few months to years, it would have been caught then, and nothing at all would have changed. Huge tumors are almost always benign and are not life-threatening. Plus, please note that the contrast agent commonly used when performing MRIs can cause serious kidney damage.