Standard type of Users can only see data items that they explicitly own, as in the Owner field of the item.
For some specific data types however, a Standard user can also see ‘children’ items linked to a parent data item if he is the Owner of the parent item. This applies for example to notes or tasks linked to a Contact/Company/Project/Deal owned by a Standard user.
We have however explicitly excluded Quotes and Invoices linked to a Contact/Company/Project/Deal from this scheme. This is because Quotes and Invoices can be viewed as sensitive financial data, which is not under the same ownership as the related Account/Client. Quotes/Invoices are the responsibility of Finance, whereas Clients are the responsibility of the Sales team members. Therefore a Standard user who owns a Contact, will not have access to quotes and invoices linked to this Contact.
If you nevertheless wish a Standard user to view a Quote/Invoice linked to a Contact he owns, you must explicitly set the user as the Owner of the Quote/Invoice.