yahoo wrote:...employees are typically forbidden from undertaking alternative employment..
This largely depends on the labour/employment laws in the legal region you live in. Where I am from an employer can generally only restrict you from passing knowledge/technique to another business (trade secrets) or working for another business that
directly competes with their own, and that
directly part is important.
eg.
If you are a Heath Care Professional who worked for two different Old Age Facilities in different suburbs then it could be argued that there is no direct competition, so the only potential issue would be if it was proven that the person passed information about one employer to the other. The same would be true for a Bartender that worked in two different Hotels under similar circumstances. If the Heath Care Professional was also the Bartender then there would be no issue whatsoever.
And in our modern world where employers are either: converting existing full-time jobs into either part-time or casual jobs; or creating new part-time or casual jobs instead of full-time jobs. Or peoples wages aren't covering the rising cost of living (or the people's needs / wants) then more people are having to have a second (or third) job just to cover their household costs, which is why our labour/employment laws are written like they are.
yahoo wrote:Patreon is to an online business what card processor is to a physical shop.
I'm not sure if this analogy is 100% correct.
In the case of an (standard) online business the 'customer' generally has a directly relationship with the business (customer data, sales history, etc..) but is using the card processor as a means to pay for the product/services provided by the business. This relationship is generally also true for an online business that is acting as a middle-man between customers and other manufactures/service-providers, like Amazon's third-party sales feature.
In the case of Patreon the 'subscriber' generally has a directly business relationship (subscriber data, payment history, etc..) with Patreon instead of the 'developer', and the 'developer' acts more like a 'suppler' of goods/services. In many ways Patreon is like Amazon's third-party sales feature, except it is subscription based instead of one-time payment based.