Who says they won't?
People all over the country are complaining about delays in getting Covid results. Most normal folk have to wait a couple days. Athletes are already getting expedited special treatment (Chris Davis had 8 tests in those two days he was off and they all came back negative by the end of the second day). As much as I am a sports fan, I'm not sure that's even right. But if some tests that were supposed to come back in 12 hours are taking 18 because the lab is overworked, I won't blame MLB.