One of the perpetual alleged threats to cross-border education is that universities in the developing world might someday rival those in the west. Once that happens, the theory goes, students won’t need to go abroad and the whole international student thing goes up in smoke. It’s not an implausible theory, but it underplays how difficult catching up actually is.

The most basic problem for universities in developing countries is paying staff. Those talented and fortunate enough to have a terminal degree (this is by no means a given at universities in many countries), are often quite mobile. Salaries not high enough at Kenyan universities? Move to Tanzania, where salaries are higher? Not high enough in Tanzania? Try South Africa. Horizons not big enough in Johannesburg? There’s always New Zealand. And so on, and so on. It’s not quite a global market – more a series of overlapping regional ones. But the point is that institutions have to pay vastly over the odds in order to keep staff.

The gaps in national pay scales are huge. In Tanzania, a full professor makes about $3000 (US) per month. That may not sound like much, but it’s about 65 times the average private sector wage. A top academic could double that by heading to South Africa, but even that is roughly six times the average private sector wage. Move to Canada or Australia and it doubles again, even though here wages of topic academics are roughly three times the average private sector wage. To put all that another way: it takes the Tanzanian state twenty times as much financial effort in relative terms in order to pay its academics a quarter of what they’d earn in the west. Now, sure, not all Tanzanian academics would make it in Western universities. Yet that’s still the price required to keep talent at home. Financially, just staying in place is a killer; moving up the quality ladder is beyond most countries’ resources.

Even where top talent can be retained either through significant salaries, major research funds or linguistic barriers, the fact is that institutional prestige isn’t just a function of talent. As my friend Jamil Salmi says, it’s the product of talent, resources, governance (a critical missing factor in too many countries) – and above all, time. Prestige is a stock, not a flow. It comes from decades of consistent growth and excellence. Even if a new university pops up with billions of dollars and a few celebrity professors – say, the King Abdullah University of Science and Technology in Saudi Arabia or Nazarbayev University in Kazakhstan – that doesn’t mean it is instantly going to gain prestige.  In fact, to be more precise: it takes decades of having graduates with great careers before anyone will think an institution to be genuinely prestigious. And not many developing-world institutions can claim such things.

And in any case, prestige is a moving target. As I noted back here, the very nature of institutional prestige is changing, shifting from being a mainly research-based institution to a mainly economic-growth-catalysing institution. And as noted back here, it’s very difficult in many developing countries for universities t play such a role, first because they have few domestic technology-intensive businesses with whom to collaborate, and second because they rarely have either the academic culture or leadership to turn them in this new direction. There are a few – NUS in Singapore, KAIST and Pohang in Korea, some of the C9 in China – that can say this. Precious few others can.

What does that mean for international education?  Prestige – however you measure it – is a lagging indicator of economic growth, not a leading one. That means that even if economic catch-up of developing countries continues, it’s going to be a loooong time before the prestige of those countries’ universities matches those of those in developed countries. That doesn’t give developed-country universities a monopoly on international students by any means; south-south student mobility is an increasing percentage of all international student flows. But it does mean that quality/prestige will remain a source of competitive advantage for these institutions for many years – maybe even decades – to come.