Typo is correct. All militaries are a product of their society (which in turn is based partly on geographic factors). Heavy infantry in the form of Greek Hoplites or Roman Legionnaries are fairly unique to the West, in the same way that armies or mass cavalry archers are mainly found in the great Eurasian steppes.
Italy and Greece are mountainous penninsulas with small areas of pastureland and easy access to the sea. It encourages a society of small, independent farmers that trade with others. The society of Greek poleis end up favoring heavy infantry based on independent farmers. They have the wealth to maintain their own weapons and armor; and their involvement in the politics of their polis encourage or obligate them to defend it. They train extensively to fight in close formation. The costs in time and money are born by individuals who willingly give it because of their own participation in the state. Nobles may fight on horseback, but the geography of the land prevents their being enough rich nobles or horses for a large cavalry force.
None of those elements apply to Persia which was dominated by cavlary on the Iranian Plateau. Their nobility fought on horseback, and was the dominant part of their armed forces. Their infantry was mainly light infantry of peasant levies. The light infantry were poorly armed and had little training in comparison to the Greek hoplites precisely because they were peasants who did not own their own land. The nobility, of course, preferred to fight on horseback as it was more prestigious than fighting on foot, and the Persians had much greater access to horses than the Greeks.
The Persian empire lacked the society to encourage the formation of heavy infantry. It would require a vastly different system of social and economic formation. It was simply easier for them to higher Greek mercenaries if they wanted such heavy infantry.
It might be possible for the Persians to decide to arm and extensively train peasants to fight as heavy infantry. But this is a high cost for very little gain. Since peasants can't own or maintain their own weapons, the state has to do it for them. And for the peasants to train extensively means they can't be working in the fields for their lords. Also, they will need to be paid/clothed/fed all this time (unlike levies of light infantry which are called only when needed). All of this is a cost that was not previously borne by the state. So taxes will need to increase which will produce social unrest. And all of this extra cost wasn't needed to create or maintain the Persian Empire in the first place. This is only being done so that obstensibly the Persian Empire can invade a marginal territory on their far western flank.
In other words, the bulk of Persian society is going to be against this increase in cost and social unrest for little potential gain.
Italy and Greece are mountainous penninsulas with small areas of pastureland and easy access to the sea. It encourages a society of small, independent farmers that trade with others. The society of Greek poleis end up favoring heavy infantry based on independent farmers. They have the wealth to maintain their own weapons and armor; and their involvement in the politics of their polis encourage or obligate them to defend it. They train extensively to fight in close formation. The costs in time and money are born by individuals who willingly give it because of their own participation in the state. Nobles may fight on horseback, but the geography of the land prevents their being enough rich nobles or horses for a large cavalry force.
None of those elements apply to Persia which was dominated by cavlary on the Iranian Plateau. Their nobility fought on horseback, and was the dominant part of their armed forces. Their infantry was mainly light infantry of peasant levies. The light infantry were poorly armed and had little training in comparison to the Greek hoplites precisely because they were peasants who did not own their own land. The nobility, of course, preferred to fight on horseback as it was more prestigious than fighting on foot, and the Persians had much greater access to horses than the Greeks.
The Persian empire lacked the society to encourage the formation of heavy infantry. It would require a vastly different system of social and economic formation. It was simply easier for them to higher Greek mercenaries if they wanted such heavy infantry.
It might be possible for the Persians to decide to arm and extensively train peasants to fight as heavy infantry. But this is a high cost for very little gain. Since peasants can't own or maintain their own weapons, the state has to do it for them. And for the peasants to train extensively means they can't be working in the fields for their lords. Also, they will need to be paid/clothed/fed all this time (unlike levies of light infantry which are called only when needed). All of this is a cost that was not previously borne by the state. So taxes will need to increase which will produce social unrest. And all of this extra cost wasn't needed to create or maintain the Persian Empire in the first place. This is only being done so that obstensibly the Persian Empire can invade a marginal territory on their far western flank.
In other words, the bulk of Persian society is going to be against this increase in cost and social unrest for little potential gain.