Does Anyone Know the REAL Roaming Costs Incurred by Carriers?

[inquisitor]

That different font is obviously a result of how your phone interprets the EF SPN-data from you SIM card.
According to 3GPP TS 31.102 there are only the following options for the EF SPN value:

• b1=0: display of registered PLMN name not required when registered PLMN is either HPLMN or a PLMN in the service provider PLMN list (see EFSPDI).
• b1=1: display of registered PLMN name required when registered PLMN is either HPLMN or a PLMN in the service provider PLMN list(see EFSPDI).
• b2=0: display of the service provider name is required when registered PLMN is neither HPLMN nor a PLMN in the service provider PLMN list(see EFSPDI).
• b2=1: display of the service provider name is not required when registered PLMN is neither HPLMN nor a PLMN in the service provider PLMN list(see EFSPDI).
  RFU (see TS 31.101)

So providers can define when to show the provider name, but not how.