Correct me if I am wrong, but from my understanding of statistics, there are games in which it is fairly easy to calculate the actual edge of the house if one is willing to gamble multiple rounds to get enough data. I assume you mean blackjack is increasingly difficult to do it because there is factor of choice by the gambler on whatever option they will take when they first receive their first to cards at the beginning of the round, it is like added entropy.
On the other hand, it comes to my mind games like coin flip, which does not have those factors and added entropy, so one could calculate the real house edge of one plays enough and keeps track on the losses and wins. I could be done with a spread sheet and enough patience.

I am a blackjack player, and sometimes when I feel like burning some time I go for some rounds and end up just wagering a few dollars, but even if I was more dedicated, I could not effectively calculate the edge, is that how it works?