The standard ZIP format relies heavily on the DEFLATE algorithm (combining LZ77 and Huffman coding). Its maximum theoretical run-length encoding limit is 1032:1 for extremely repetitive identical bytes, because the longest single repeated sequence it can encode is 258 bytes using specific bit lengths

Such compression relies on repeated information, something GTA certainly lacks when compared to Minecraft. Minecraft worlds are a different story given there's like what? A few dozen or more block types? Most being stone, grass and sand.