Why manufacturers can do this now
Modern inkjet glazing applies incredibly high-resolution imagery directly to the tile surface before firing, letting manufacturers reproduce the veining and depth of Carrara, Calacatta, and Statuario marble with far more nuance than older print methods allowed.
The tell: pattern repeat
The biggest giveaway on a lower-end line isn't the color or veining detail — it's repetition. If a floor only draws from one or two unique tile faces, the pattern visibly repeats every few tiles once you lay it out at scale. Better lines offer four to six or more unique faces per pattern specifically to avoid this.
What you're trading away
Even the best marble-look porcelain won't have the cool, natural feel of real stone underfoot, and the veining, while varied, is still a finite, repeating set rather than truly infinite natural variation. For most kitchens and bathrooms, that trade-off is easily worth the zero-maintenance upside.