A productive weekend ...
Metrics for tangible things such as trees are more straightforward than for intangible things such as risks. We can easily see the progress being made as the tree is cleared, estimate how much work remains, calculate the value earned and so on. We could measure the height, spread and volume of the foliage section with a tape measure (or use a ruler on the photographs above), and weigh the firewood using scales. You could potentially verify our measurements, using your own measures and scales. We might need to convert the units, but the units of measure and the conversion factors are scientifically determined and generally agreed. There would inevitably be discrepancies in the measured values (we may need to repeat them or adopt other measurement methods) and estimates (such as the value of firewood). We might need to clarify certain parameters such as exactly what constitutes 'the foliage section'. With care it ought to be possible to get our measurements and calculations to within, say, 20%.
We could also assess the risk factors involved in the tree-clearance job and come up with our risk measures, but you would probably think of different factors and use different measures. We would struggle to get our measures 'on the same page', let alone within 20%. We might be thinking of health and safety risks, while you might be concerned about financial risks, or the risk of bad weather or whatever. On the other hand, discussing our differences would be quite revealing in terms of deepening and broadening our understanding the risks - and often that's the real value of risk analysis: the numbers themselves aren't the most important goal. Knowing about the risks involved in the situation in order to treat them sensibly is a more valuable outcome.
Amazing how much the mind wanders when I'm chainsawing logs!