Why does Trotterization introduce error?

Because each time step is measured and re-prepared, so the accumulated collapse error grows with the step count

Because non-commuting Hamiltonian terms make the state vector too large to hold, forcing the amplitudes to be rounded

Because non-commuting Hamiltonian terms cannot generally be exponentiated independently without approximation

Because every Hamiltonian term commutes, so their order in the product is chosen at random by the compiler