There are a number of categories of expenditure which can be either capital or revenue in nature (depending on case law) or are capital items with write off provisions attached (eg borrowing costs). Someone actually made this suggestion in the context of a senate inquiry a few years ago - why not simply have statutory maximums set for these kinds of expenses so that people can treat these items as revenue and write them off in the year incurred.
A prime example is legal expenses. Businesses seek advice about many issues that potentially straddle issues of both capital and revenue. These kinds of things cause endless arguments in the context of audits, when it is really just a timing difference.
Given the latitude around instant asset write offs these days, it is incongruous to treat this other minor capital expenditure differently. I would suggest that $50,000 per annum for a corporation and $10,000 for a sole trader would be a good start.