Hi,
I know exactly what you are saying. I hate to say that but I did the same mistake and did not read the documentation.
TL;TR Cashier is only for subscriptions, use Stripe SDK instead.
Introduction Laravel Cashier provides an expressive, fluent interface to Stripe's and Braintree's subscription billing services. It handles almost all of the boilerplate subscription billing code you are dreading writing. In addition to basic subscription management, Cashier can handle coupons, swapping subscription, subscription "quantities", cancellation grace periods, and even generate invoice PDFs.
If you're only performing "one-off" charges and do not offer subscriptions, you should not use Cashier. Instead, use the Stripe and Braintree SDKs directly.
Hope it helps!