You can claim child care costs. As well as subsistence (even though they provide lunch), and travel on top of the loss of earnings. The first week rate is poor, but after that the rate is about £130/day, tax free. With travel and childcare it’s probably not far off the net equivalent of 45k p.a. Whilst your wife might earn more than that and won’t get any more you probably aren’t going to gain too much sympathy, especially as most cases only last 2-3 weeks at the very most. Whilst I understand the frustration (our policy is to top up the allowance to actual salary provided the employee keeps in touch e.g. By checking email before and after court – which only sits from about 10-4) it is an important civic duty – one day you could find yourself in the dock (or the victim of a crime) and would hope for a representative jury.
What amazes me is people only get animated about this when cited, but we all know we could be cited at any time.