Should I be concerned about the validity of my degree if my peers in other educational systems seem to have more difficult exams?
Comparing different educational systems is frequently a futile exercise. Learning is like hiking to the top of a mountain from different trails: all of them lead to the same top, but one can be very steep at the beginning, a second one can have its steepest segment halfway to the top and a third one can have a final wall that needs an expert climber. Different educational systems can choose different paths according to different intermediate objectives.
Though it's true that some people prefer a certain type of trail with respect to another, and that along certain trails one can find more people with whom to share the joys and sorrows of hiking (learning), arriving to the top depends only on your efforts.
Now you are at the beginning of your trail. It's too early to decide whether it's a good trail or not: start hiking and enjoy the landscape, and if you think that the trail is not enough steep for your training, try to jog or run uphill. In other words, challenge yourself: you will learn much much more.

An anecdote about the appropriateness of certain steep starts. When I was a sophomore (2nd year) studying electronic engineering we had a mandatory class called Rational Mechanics, about Lagrangian and Hamiltonian mechanics. The exam consisted in a set of problems on mechanical systems to be solved with those two formalisms, a home project in which we had to develop a numerical solver with different techniques (in Pascal), and a viva where we had to prove various theorems. It was a tough exam at the sophomore level, but mostly because no one could really get the grasp of it. I somehow managed to tunnel through the exam, even with a decent grade.
Two years later I attended a class on quantum mechanics. The first lecture the professor said something like: &quot;Quantum mechanics is based on Hamiltonian mechanics, and since you already know it we can proceed quickly&quot;. I then timidly raised my hand and said &quot;Er... no one in this room has the faintest idea of what Hamiltonian mechanics is. Yes, we passed the exam two years ago, but really... could you please give us a refresher?&quot;. She was astonished, but then agreed to spend a few lectures on Lagrangian and Hamiltonian mechanics. I integrated her lectures with a classic book, and since then those topics have been among my favourites.
The above example is to say that sometimes a tough exam at the beginning is just a misplaced exam, because some topics require a certain level of scientific maturity to be properly understood.