Take a look at formulas here, Fit Model in Recurrence Analysis, for Homogeneous Poisson Process (HPP) and other non-homogeneous Poisson processes (NHPP). The intensity function of HPP is not a function of time t. The intensity functions of NHPP are functions of time t.
So the homogeneity test is to see whether the intensity function (failure rate) is changing over time.
The homogeneity test for Power NHPP is to test beta == 1. The test for Proportional Intensity NHPP is to test delta == 1. And the test for Loglear NHPP is to test delta == 0. If you put these numbers back into the formula, you should see time disappear from the formulas.
HPP is a simpler model than NHPP's. If tests cannot reject HPP, one may prefer using HPP for further decision making.
If the process is indeed HPP, the inter-arrival times are iid Exponential distributed. But one should not analyze inter-arrival times as iid to determine whether a process is HPP.