Sounds similar to Technical Pay here. The small allowances are not enough in most cases to retain people.
Even those on Tech 6, the highest rate of allowance, are on around €6000 more than the standard rate of pay. An IT guru Sgt is still on well under €50,000 gross a year. When he can walk into another job starting on €70,000 and not have to deal with any of the inconveniences of being in the Defence Forces