Yet, unlike the Italian, the Spanish settler transition was incomplete. Indeed, counterintuitively, the Spanish "actually assimilated to the new land more slowly and more reluctantly than did the "alien" Italians", who were not quick. The Spanish rate of return was lower than the Italian, but still high at 46 percent by 1930, and in-marriage and voluntary segregation was high in both groups. Above all, both Spanish and Italian immigrants avoided Argentine citizenship like the plague. Fewer than 4 per cent of Spanish took citizenship, and the Italian rate was below 2 per cent. Immigrants received most legal rights without citizenship, with the important exception of voting in national elections. Aliens were also not liable for military service. There was therefore "no incentive to become a citizen", and a considerable disincentive. Nativist fears among the lower classes, and the fear of political competition among the elite, led Argentines to accept this situation. Immigrants dominated the Argentine lower middle classes…The incomplete settler transition therefore meant that booming Argentina's middle class was much less committed to it, much less politically powerful, and much more prone to send or take its money home, than in the Anglo newlands. The power and novelty of Spanish settler transitions helps explain Argentina's relative success to the 1920s. But the incomplete nature of the settler transition also helps explain Argentina's relative failure from the 1920s.
That is from James Belich's Replenishing the Earth: The Settler Revolution and the Rise of the Anglo World, 1783-1939.