To be honest I think most small saas are not compliant.
When you are doing low revenue numbers like this guy under 100-200K per year its hardly ever relevant.
A lot of countries and states don't claim sales tax to international countries under a certain treshold: 30 - 100K per year. (if you are selling to consumers would actually be a waste to charge sales tax)
The EU is different, but if you are in the EU relatively easy to comply with.
In EU it's easy if you have their VAT numbers, otherwise you just have to charge it. If you have EU VAT nr it's actually work for your EU customers, they have to pay for it without it being on the invoice.
When you are doing low revenue numbers like this guy under 100-200K per year its hardly ever relevant.
A lot of countries and states don't claim sales tax to international countries under a certain treshold: 30 - 100K per year. (if you are selling to consumers would actually be a waste to charge sales tax)
The EU is different, but if you are in the EU relatively easy to comply with.