I had thought of the same thing before, they are like kindred spirits. Why not merge?
Phyletism perhaps? But it has been so many generations these groups should be long since past that nonsense. Both groups have pretty mixed ethnic composition these days, despite their names.
The TAC might be anxious to preserve it’s “Englishness”, while the PNCC might be anxious to preserve it’s “Polishness”. They are actually using two different versions of the Latin liturgy. The PNCC, an American church, uses the Gregorian “Tridentine” liturgy in English (and Polish in some places) while the TAC is international in scope, but uses the Sarum-based Anglican liturgy.
On another note, the PNCC has been negotiating with Latin bishops off-and-on for decades, but they seem less enamored of the Papacy than the TAC at present. Theologically the PNCC might be more comfortable in communion with the Orthodox, but the first generations of that group would have been strongly prejudiced against the (mostly Orthodox) Russians and Ukrainians. That does not seem to be the case for the TAC, these would have little to no prejudice against Orthodox nationalities in general while at the same time are more committed to the idea of ‘Papacy’.
Origins have a lot to do with this. The PNCC was born under the cloud of abuse of their communities by Latin (mostly Irish) bishops, within decades of Vatican I. There was still some residual shock and doubt over the Papal dogmas in the ranks of the priesthood at the time. The bad handling of the Polish immigrants triggered the schism, just like similarly bad handling of Ruthenian and Ukrainian Catholics provoked a return to Orthodoxy in the same time period.
The TAC shares none of that recent history, it seems to owe more to the Oxford Movement than anything else. They were not directly impacted by Vatican I, nor did they suffer discrimination at the hands of Latin bishops within memory.
They really should talk to each other, it might help them both come to some resolution. They are not apples and oranges, but they are certainly two very different kinds of apple.